Chapter 4: Newton's Second Law Of Motion, Force And Acceleration

1. When a falling object has reached its terminal velocity, its acceleration

Constant

Zero

G

When a falling object has reached its terminal velocity, its acceleration becomes zero. Terminal velocity is the maximum velocity that an object can attain while falling through a fluid, such as air. Initially, the object accelerates due to the force of gravity. However, as the object gains speed, the upward drag force exerted by the fluid increases, eventually balancing out the force of gravity. At this point, the net force on the object becomes zero, resulting in zero acceleration. Therefore, the correct answer is zero.

Explanation

When a falling object has reached its terminal velocity, its acceleration becomes zero. Terminal velocity is the maximum velocity that an object can attain while falling through a fluid, such as air. Initially, the object accelerates due to the force of gravity. However, as the object gains speed, the upward drag force exerted by the fluid increases, eventually balancing out the force of gravity. At this point, the net force on the object becomes zero, resulting in zero acceleration. Therefore, the correct answer is zero.

2. Whenever the net force on an object is zero, its acceleration

May be less than zero

Is zero

May be more than zero

When the net force on an object is zero, it means that all the forces acting on the object are balanced and cancel each other out. In this case, the object's acceleration will be zero. This is because acceleration is directly proportional to the net force acting on an object according to Newton's second law of motion. If the net force is zero, there is no unbalanced force to cause acceleration, resulting in a zero acceleration.

Explanation

When the net force on an object is zero, it means that all the forces acting on the object are balanced and cancel each other out. In this case, the object's acceleration will be zero. This is because acceleration is directly proportional to the net force acting on an object according to Newton's second law of motion. If the net force is zero, there is no unbalanced force to cause acceleration, resulting in a zero acceleration.

3. An object is pulled northward by a force of 10 N and at the same time another force of 15 N pulls it southward. The magnitude of the resultant force on the object is

0 N

5 N

25 N

150 N

The magnitude of the resultant force on the object is 5 N because the forces pulling in opposite directions will cancel each other out partially. The northward force of 10 N will be partially counteracted by the southward force of 15 N, resulting in a net force of 5 N in the northward direction.

Explanation

The magnitude of the resultant force on the object is 5 N because the forces pulling in opposite directions will cancel each other out partially. The northward force of 10 N will be partially counteracted by the southward force of 15 N, resulting in a net force of 5 N in the northward direction.

4. A man weighing 800 N stands at rest on two bathroom scales so that his weight is distributed evenly over both scales. The reading on each scale is

200 N

400 N

800 N

1600 N

None of these

When the man stands at rest on two bathroom scales, his weight is distributed evenly over both scales. This means that each scale is supporting half of his weight. Since his weight is 800 N, each scale will read half of that, which is 400 N. Therefore, the reading on each scale is 400 N.

Explanation

When the man stands at rest on two bathroom scales, his weight is distributed evenly over both scales. This means that each scale is supporting half of his weight. Since his weight is 800 N, each scale will read half of that, which is 400 N. Therefore, the reading on each scale is 400 N.

5. When a woman stands at rest with both feet on a scale, it reads 500 N. When she gently lifts one foot, the scale reads

Less than 500 N

More than 500 N

500 N

When a woman stands at rest with both feet on a scale, the scale reads 500 N because it is measuring the force exerted by her body on the scale. When she gently lifts one foot, the scale will still read 500 N because the force exerted by her body on the scale remains the same. The scale is measuring the total force exerted by the woman's body, not just the force exerted by her feet.

Explanation

When a woman stands at rest with both feet on a scale, the scale reads 500 N because it is measuring the force exerted by her body on the scale. When she gently lifts one foot, the scale will still read 500 N because the force exerted by her body on the scale remains the same. The scale is measuring the total force exerted by the woman's body, not just the force exerted by her feet.

6. A rock is thrown vertically into the air. At the very top of its trajectory the net force on it is

Less than its weight

More than its weight

Equal to its weight

At the very top of its trajectory, the rock is momentarily at rest before it starts to fall back down. This means that its acceleration is zero, and according to Newton's second law, the net force acting on an object is equal to its mass multiplied by its acceleration. Since the acceleration is zero, the net force on the rock must also be zero. However, the weight of an object is the force due to gravity acting on it, and it always acts downwards. Therefore, at the very top of its trajectory, the net force on the rock is equal to its weight.

Explanation

At the very top of its trajectory, the rock is momentarily at rest before it starts to fall back down. This means that its acceleration is zero, and according to Newton's second law, the net force acting on an object is equal to its mass multiplied by its acceleration. Since the acceleration is zero, the net force on the rock must also be zero. However, the weight of an object is the force due to gravity acting on it, and it always acts downwards. Therefore, at the very top of its trajectory, the net force on the rock is equal to its weight.

7. A force is a vector quantity because it has both

Magnitude and direction

Mass and acceleration

Action and reaction counterparts

A force is considered a vector quantity because it has both magnitude and direction. Magnitude refers to the size or strength of the force, while direction indicates the path or orientation in which the force is applied. These two components are essential in fully describing a force and understanding its effects on an object or system.

Explanation

A force is considered a vector quantity because it has both magnitude and direction. Magnitude refers to the size or strength of the force, while direction indicates the path or orientation in which the force is applied. These two components are essential in fully describing a force and understanding its effects on an object or system.

8. A bag of groceries has a mass of 10 kilograms and a weight of

About 1 N

About 10 N

About 100 N

About 1000 N

More than 1000 N

The weight of an object is the force exerted on it due to gravity. The weight is directly proportional to the mass of the object. In this case, the bag of groceries has a mass of 10 kilograms, so its weight can be calculated using the formula weight = mass x acceleration due to gravity. The acceleration due to gravity is approximately 9.8 m/s^2. So, weight = 10 kg x 9.8 m/s^2 = 98 N. Therefore, the weight of the bag of groceries is about 100 N.

Explanation

The weight of an object is the force exerted on it due to gravity. The weight is directly proportional to the mass of the object. In this case, the bag of groceries has a mass of 10 kilograms, so its weight can be calculated using the formula weight = mass x acceleration due to gravity. The acceleration due to gravity is approximately 9.8 m/s^2. So, weight = 10 kg x 9.8 m/s^2 = 98 N. Therefore, the weight of the bag of groceries is about 100 N.

9. A 1-kg mass at the Earth's surface weighs

1 N

4.9 N

9.8 N

10.8 N

None of these

The weight of an object is the force exerted on it due to gravity. On Earth's surface, the acceleration due to gravity is approximately 9.8 m/s^2. Using the formula weight = mass x acceleration due to gravity, we can calculate the weight of a 1-kg mass to be 9.8 N.

Explanation

The weight of an object is the force exerted on it due to gravity. On Earth's surface, the acceleration due to gravity is approximately 9.8 m/s^2. Using the formula weight = mass x acceleration due to gravity, we can calculate the weight of a 1-kg mass to be 9.8 N.

10. A girl pulls on a 10-kg wagon with a constant horizontal force of 30 N. If there are no other horizontal forces, what is the wagon's acceleration in meters per second per second?

0.3

3.0

10

30

300

The wagon's acceleration can be calculated using Newton's second law, which states that the force applied to an object is equal to the mass of the object multiplied by its acceleration. In this case, the force applied to the wagon is 30 N and the mass of the wagon is 10 kg. Therefore, the acceleration of the wagon is 30 N / 10 kg = 3.0 m/s^2.

Explanation

The wagon's acceleration can be calculated using Newton's second law, which states that the force applied to an object is equal to the mass of the object multiplied by its acceleration. In this case, the force applied to the wagon is 30 N and the mass of the wagon is 10 kg. Therefore, the acceleration of the wagon is 30 N / 10 kg = 3.0 m/s^2.

11. A 10-N falling object encounters 10 N of air resistance. The net force on the object is

0 N

4 N

6 N

10 N

None of these

When an object is falling, it experiences two forces: gravity pulling it downward and air resistance pushing it upward. In this case, the object encounters 10 N of air resistance, which cancels out the 10 N force of gravity. Therefore, the net force on the object is 0 N.

Explanation

When an object is falling, it experiences two forces: gravity pulling it downward and air resistance pushing it upward. In this case, the object encounters 10 N of air resistance, which cancels out the 10 N force of gravity. Therefore, the net force on the object is 0 N.

12. A kilogram is a measure of an object's

Weight

Force

Mass

Size

A kilogram is a measure of an object's mass. Mass refers to the amount of matter in an object, and it remains the same regardless of the object's location or the force acting on it. Weight, on the other hand, is the force exerted on an object due to gravity and can vary depending on the object's location. Size is a measure of an object's dimensions and is unrelated to mass. Therefore, the correct answer is mass.

Explanation

A kilogram is a measure of an object's mass. Mass refers to the amount of matter in an object, and it remains the same regardless of the object's location or the force acting on it. Weight, on the other hand, is the force exerted on an object due to gravity and can vary depending on the object's location. Size is a measure of an object's dimensions and is unrelated to mass. Therefore, the correct answer is mass.

13. The force of friction on a sliding object is 10 newtons. The applied force needed to maintain a constant velocity is

More than 10 N

Less than 10 N

10 N

The applied force needed to maintain a constant velocity is equal to the force of friction. In this case, the force of friction is 10 newtons, so the applied force needed to maintain a constant velocity is also 10 newtons.

Explanation

The applied force needed to maintain a constant velocity is equal to the force of friction. In this case, the force of friction is 10 newtons, so the applied force needed to maintain a constant velocity is also 10 newtons.

14. An object following a straight-line path at constant speed

Has a net force acting upon it in the direction of motion

Has zero acceleration

Has no forces acting on it

None of these

An object following a straight-line path at constant speed has zero acceleration. This is because acceleration is the rate of change of velocity, and if the object is moving at a constant speed, its velocity is not changing. Therefore, there is no acceleration.

Explanation

An object following a straight-line path at constant speed has zero acceleration. This is because acceleration is the rate of change of velocity, and if the object is moving at a constant speed, its velocity is not changing. Therefore, there is no acceleration.

15. If less horizontal force is applied to a sliding object than is needed to maintain a constant velocity

The object accelerates in the direction of the applied force

The friction force increases

The object eventually slides to a stop

None of the above

If less horizontal force is applied to a sliding object than is needed to maintain a constant velocity, the object eventually slides to a stop. This is because the force applied is not enough to counteract the opposing forces such as friction, air resistance, or any other resistance that may be acting on the object. As a result, the object gradually loses its velocity and comes to a stop.

Explanation

If less horizontal force is applied to a sliding object than is needed to maintain a constant velocity, the object eventually slides to a stop. This is because the force applied is not enough to counteract the opposing forces such as friction, air resistance, or any other resistance that may be acting on the object. As a result, the object gradually loses its velocity and comes to a stop.

16. A sack of potatoes weighing 200 N falls from an airplane. As the velocity of fall increases, air resistance also increases. When air resistance equals 200 N, the sack's acceleration in meters per second per second is

0

4.9

9.8

Infinite

None of these

When air resistance equals the weight of the sack (200 N), the net force on the sack becomes zero. According to Newton's second law of motion, F = ma, where F is the net force, m is the mass, and a is the acceleration. Since the net force is zero, the acceleration of the sack is also zero. Therefore, the correct answer is 0.

Explanation

When air resistance equals the weight of the sack (200 N), the net force on the sack becomes zero. According to Newton's second law of motion, F = ma, where F is the net force, m is the mass, and a is the acceleration. Since the net force is zero, the acceleration of the sack is also zero. Therefore, the correct answer is 0.

17. A car traveling at 22 m/s comes to an abrupt halt in 0.1 second when it hits a tree. What is the deceleration in meters per second per second of the car?

110

220

800

880

Can't be solved without the mass of the car

The deceleration of the car can be calculated using the formula: deceleration = change in velocity / time. In this case, the change in velocity is from 22 m/s to 0 m/s, which is a decrease of 22 m/s. The time taken for this change is 0.1 seconds. Therefore, the deceleration is 22 m/s / 0.1 s = 220 m/s^2.

Explanation

The deceleration of the car can be calculated using the formula: deceleration = change in velocity / time. In this case, the change in velocity is from 22 m/s to 0 m/s, which is a decrease of 22 m/s. The time taken for this change is 0.1 seconds. Therefore, the deceleration is 22 m/s / 0.1 s = 220 m/s^2.

18. Which has the greater mass?

A king-size pillow

An automobile battery

) neither – both have the same

An automobile battery has a greater mass compared to a king-size pillow. This is because automobile batteries are generally made of heavy materials such as lead and have a larger size and weight compared to a pillow, which is typically filled with lightweight materials like feathers or synthetic fibers. Therefore, the battery would have a greater mass.

Explanation

An automobile battery has a greater mass compared to a king-size pillow. This is because automobile batteries are generally made of heavy materials such as lead and have a larger size and weight compared to a pillow, which is typically filled with lightweight materials like feathers or synthetic fibers. Therefore, the battery would have a greater mass.

19. A 1-kg rock that weighs 9.8 N is thrown straight upward at 20 m/s. Neglecting air resistance, the net force that acts on it when it is half way to the top of its path is

Less than 9.8 N

9.8 N

More than 9.8 N

When the rock is halfway to the top of its path, it has already reached its maximum height and is momentarily at rest before falling back down. At this point, the net force acting on the rock is equal to its weight, which is 9.8 N. This is because the only force acting on the rock is gravity, which pulls it downward with a force equal to its weight. Therefore, the correct answer is 9.8 N.

Explanation

When the rock is halfway to the top of its path, it has already reached its maximum height and is momentarily at rest before falling back down. At this point, the net force acting on the rock is equal to its weight, which is 9.8 N. This is because the only force acting on the rock is gravity, which pulls it downward with a force equal to its weight. Therefore, the correct answer is 9.8 N.

20. A 10-N block and a 1-N block lie on a horizontal frictionless table. To provide them with equal horizontal acceleration, we would have to push with

Equal forces on each block

10 times as much force on the heavier block

10 squared or 100 times as much force on the heavier block

1/10 as much force on the heavier block

None of these

To provide equal horizontal acceleration to both blocks, we need to apply a force that overcomes the inertia of each block. The force required to overcome inertia is directly proportional to the mass of the object. Since the 10-N block is heavier than the 1-N block, it has more inertia and therefore requires a greater force to accelerate it. Therefore, we would have to push with 10 times as much force on the heavier block.

Explanation

To provide equal horizontal acceleration to both blocks, we need to apply a force that overcomes the inertia of each block. The force required to overcome inertia is directly proportional to the mass of the object. Since the 10-N block is heavier than the 1-N block, it has more inertia and therefore requires a greater force to accelerate it. Therefore, we would have to push with 10 times as much force on the heavier block.

21. A jumbo jet has a mass of 100,000 kg. The thrust for each of its four engines is 50,000 N. What is the jet's acceleration in meters per second per second when taking off?

0.25

1

2

4

None of these

The acceleration of the jumbo jet can be calculated using Newton's second law of motion, which states that force is equal to mass multiplied by acceleration. In this case, the total force exerted by the four engines is 50,000 N * 4 = 200,000 N. Dividing this force by the mass of the jet (100,000 kg) gives us the acceleration, which is 200,000 N / 100,000 kg = 2 meters per second per second.

Explanation

The acceleration of the jumbo jet can be calculated using Newton's second law of motion, which states that force is equal to mass multiplied by acceleration. In this case, the total force exerted by the four engines is 50,000 N * 4 = 200,000 N. Dividing this force by the mass of the jet (100,000 kg) gives us the acceleration, which is 200,000 N / 100,000 kg = 2 meters per second per second.

22. A skydiver's terminal velocity will be greatest if she falls

Head first

Lying flat on her back

Lying flat on her stomach

With her parachute open

When a skydiver falls head first, their body position creates the least amount of air resistance. This allows them to reach their maximum speed, known as terminal velocity, more quickly. By reducing air resistance, the skydiver can accelerate faster and reach a higher velocity compared to other body positions.

Explanation

When a skydiver falls head first, their body position creates the least amount of air resistance. This allows them to reach their maximum speed, known as terminal velocity, more quickly. By reducing air resistance, the skydiver can accelerate faster and reach a higher velocity compared to other body positions.

23. If an object of constant mass experiences a constant net force, it will have a constant

Velocity

Speed

Acceleration

Position

More than one of the above

If an object of constant mass experiences a constant net force, according to Newton's second law of motion, the object will have a constant acceleration. This is because the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. Therefore, if the mass remains constant and the net force is constant, the object will experience a constant acceleration.

Explanation

If an object of constant mass experiences a constant net force, according to Newton's second law of motion, the object will have a constant acceleration. This is because the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. Therefore, if the mass remains constant and the net force is constant, the object will experience a constant acceleration.

24. A 10-N falling object encounters 4 N of air resistance. The net force on the object is

0 N

4 N

6 N

10 N

None of these

The net force on the object is 6 N because it is the difference between the force of gravity (10 N) and the force of air resistance (4 N). The net force is the overall force acting on the object, taking into account both the forces acting in the same direction and those acting in opposite directions. In this case, the force of gravity is acting downwards, while the force of air resistance is acting upwards. Therefore, the net force is the difference between these two forces, resulting in a net force of 6 N acting downwards on the object.

Explanation

The net force on the object is 6 N because it is the difference between the force of gravity (10 N) and the force of air resistance (4 N). The net force is the overall force acting on the object, taking into account both the forces acting in the same direction and those acting in opposite directions. In this case, the force of gravity is acting downwards, while the force of air resistance is acting upwards. Therefore, the net force is the difference between these two forces, resulting in a net force of 6 N acting downwards on the object.

25. A push on a 1-kg brick accelerates it. Neglecting friction, to equally accelerate a 10-kg brick, one would have to push with

Just as much force

10 times as much force

100 times as much force

One-tenth the amount of force

None of these

To equally accelerate a 10-kg brick, one would have to push with 10 times as much force. This is because according to Newton's second law of motion, the force applied on an object is directly proportional to its mass and acceleration. In this case, the mass of the 10-kg brick is 10 times greater than the 1-kg brick, so to achieve the same acceleration, the force applied must also be 10 times greater.

Explanation

To equally accelerate a 10-kg brick, one would have to push with 10 times as much force. This is because according to Newton's second law of motion, the force applied on an object is directly proportional to its mass and acceleration. In this case, the mass of the 10-kg brick is 10 times greater than the 1-kg brick, so to achieve the same acceleration, the force applied must also be 10 times greater.

26. A tow truck exerts a force of 3000 N on a car, accelerating it at 2 meters per second per second. What is the mass of the car?

500 kg

1000 kg

1500 kg

3000 kg

None of these

The mass of an object can be determined using the formula F = ma, where F is the force exerted on the object and a is the acceleration. In this case, the force exerted by the tow truck is 3000 N and the acceleration of the car is 2 m/s^2. Plugging these values into the formula, we get 3000 N = m * 2 m/s^2. Solving for m, we find that the mass of the car is 1500 kg.

Explanation

The mass of an object can be determined using the formula F = ma, where F is the force exerted on the object and a is the acceleration. In this case, the force exerted by the tow truck is 3000 N and the acceleration of the car is 2 m/s^2. Plugging these values into the formula, we get 3000 N = m * 2 m/s^2. Solving for m, we find that the mass of the car is 1500 kg.

27. A falling skydiver of mass 100 kg experiences 500 N of air resistance. The acceleration of the skydiver is

0.2 g

0.3 g

0.4 g

0.5

More than 0.5 g

The skydiver is experiencing air resistance, which is acting in the opposite direction to the force of gravity. The acceleration of the skydiver can be determined using Newton's second law of motion, which states that force is equal to mass times acceleration. The force of gravity acting on the skydiver can be calculated using the formula F = mg, where m is the mass of the skydiver and g is the acceleration due to gravity. In this case, the force of gravity is 100 kg * 9.8 m/s^2 = 980 N. Since the air resistance is 500 N, the net force acting on the skydiver is 980 N - 500 N = 480 N. Using Newton's second law, we can determine the acceleration of the skydiver: 480 N = 100 kg * a, where a is the acceleration. Solving for a gives us a = 480 N / 100 kg = 4.8 m/s^2. To express the acceleration in terms of g, we divide by the acceleration due to gravity: 4.8 m/s^2 / 9.8 m/s^2 = 0.49 g. Since the question asks for the acceleration in terms of g, the correct answer is 0.5 g.

Explanation

The skydiver is experiencing air resistance, which is acting in the opposite direction to the force of gravity. The acceleration of the skydiver can be determined using Newton's second law of motion, which states that force is equal to mass times acceleration. The force of gravity acting on the skydiver can be calculated using the formula F = mg, where m is the mass of the skydiver and g is the acceleration due to gravity. In this case, the force of gravity is 100 kg * 9.8 m/s^2 = 980 N. Since the air resistance is 500 N, the net force acting on the skydiver is 980 N - 500 N = 480 N. Using Newton's second law, we can determine the acceleration of the skydiver: 480 N = 100 kg * a, where a is the acceleration. Solving for a gives us a = 480 N / 100 kg = 4.8 m/s^2. To express the acceleration in terms of g, we divide by the acceleration due to gravity: 4.8 m/s^2 / 9.8 m/s^2 = 0.49 g. Since the question asks for the acceleration in terms of g, the correct answer is 0.5 g.

28. Your weight is

Equal to your mass

The gravitational attraction force between you and the Earth

A property of mechanical equilibrium

All of these

The correct answer is "the gravitational attraction force between you and the Earth." Weight is the force exerted on an object due to gravity, and it is directly proportional to an object's mass. Therefore, your weight is equal to the gravitational attraction force between you and the Earth.

Explanation

The correct answer is "the gravitational attraction force between you and the Earth." Weight is the force exerted on an object due to gravity, and it is directly proportional to an object's mass. Therefore, your weight is equal to the gravitational attraction force between you and the Earth.

29. A light woman and a heavy man jump from an airplane at the same time and open their same-size parachutes at the same time. Which person will get to a state of zero acceleration first?

The light woman

The heavy man

Both should arrive at the same time

Not enough information

The light woman will get to a state of zero acceleration first because her smaller mass means that there is less force acting on her due to gravity. This allows her to reach a state of zero acceleration more quickly than the heavy man.

Explanation

The light woman will get to a state of zero acceleration first because her smaller mass means that there is less force acting on her due to gravity. This allows her to reach a state of zero acceleration more quickly than the heavy man.

30. The mass of a pet turtle that weighs 10 N is

About 1 kg

About 10 kg

About 100 kg

About 1000 kg

None of these

The weight of an object is equal to the force of gravity acting on it, which is given by the equation weight = mass * acceleration due to gravity. In this case, the turtle weighs 10 N, which means the force of gravity acting on it is 10 N. Since the acceleration due to gravity is approximately 9.8 m/s^2, we can rearrange the equation to solve for mass: mass = weight / acceleration due to gravity. Substituting the given values, we find that the mass of the turtle is approximately 1 kg.

Explanation

The weight of an object is equal to the force of gravity acting on it, which is given by the equation weight = mass * acceleration due to gravity. In this case, the turtle weighs 10 N, which means the force of gravity acting on it is 10 N. Since the acceleration due to gravity is approximately 9.8 m/s^2, we can rearrange the equation to solve for mass: mass = weight / acceleration due to gravity. Substituting the given values, we find that the mass of the turtle is approximately 1 kg.

31. An object's weight may properly be expressed in units of

Meters

Kilograms

Newtons

Cubic centimeters

An object's weight is a measure of the force exerted on it due to gravity. The unit of measurement for force is newtons. Therefore, it is appropriate to express an object's weight in newtons. Meters, kilograms, and cubic centimeters are units of length, mass, and volume respectively, and are not suitable for measuring weight.

Explanation

An object's weight is a measure of the force exerted on it due to gravity. The unit of measurement for force is newtons. Therefore, it is appropriate to express an object's weight in newtons. Meters, kilograms, and cubic centimeters are units of length, mass, and volume respectively, and are not suitable for measuring weight.

32. A ball thrown straight upward takes 10 seconds to go up and return to the ground. Because of air resistance, the time taken for the ball just to go up is

Less than 5 s

More than 5 s

5 s

The correct answer is less than 5 s. This is because air resistance slows down the upward motion of the ball, causing it to take longer to reach its maximum height. Therefore, the time taken for the ball to just go up is less than the total time of 10 seconds.

Explanation

The correct answer is less than 5 s. This is because air resistance slows down the upward motion of the ball, causing it to take longer to reach its maximum height. Therefore, the time taken for the ball to just go up is less than the total time of 10 seconds.

33. A block is dragged without acceleration in a straight-line path across a level surface by a force of 6 N. What is the force of friction between the block and the surface?

Less than 6 N

More than 6 N

6 N

Need more information to say

The force of friction between the block and the surface is 6 N because the block is being dragged without acceleration. According to Newton's first law of motion, if an object is moving with constant velocity, the net force acting on it must be zero. In this case, the force of friction is equal in magnitude and opposite in direction to the applied force of 6 N, resulting in a net force of zero. Therefore, the force of friction must also be 6 N.

Explanation

The force of friction between the block and the surface is 6 N because the block is being dragged without acceleration. According to Newton's first law of motion, if an object is moving with constant velocity, the net force acting on it must be zero. In this case, the force of friction is equal in magnitude and opposite in direction to the applied force of 6 N, resulting in a net force of zero. Therefore, the force of friction must also be 6 N.

34. Compared to the mass of a certain object on Earth, the mass of the same object on the moon is

One sixth as much

The same

Six times as much

Zero

The mass of an object remains the same regardless of its location. Therefore, the mass of a certain object on the moon would be the same as its mass on Earth.

Explanation

The mass of an object remains the same regardless of its location. Therefore, the mass of a certain object on the moon would be the same as its mass on Earth.

35. A 500-N parachutist opens his chute and experiences an air resistance force of 800 N. The net force on the parachutist is

300 N downward

500 N downward

800 N downward

300 N upward

500 N upward

When the parachutist opens his chute, he experiences an air resistance force of 800 N. The force of air resistance acts in the opposite direction to the force of gravity, which is 500 N downward. The net force on an object is the vector sum of all the forces acting on it. In this case, the net force is the difference between the force of gravity and the force of air resistance, which is 500 N downward minus 800 N upward. Thus, the net force on the parachutist is 300 N upward.

Explanation

When the parachutist opens his chute, he experiences an air resistance force of 800 N. The force of air resistance acts in the opposite direction to the force of gravity, which is 500 N downward. The net force on an object is the vector sum of all the forces acting on it. In this case, the net force is the difference between the force of gravity and the force of air resistance, which is 500 N downward minus 800 N upward. Thus, the net force on the parachutist is 300 N upward.

36. A skydiver, who weighs 500 N, reaches terminal velocity of 90 km/h. The air resistance on the diver is then

90 N

250 N

410 N

500 N

None of these

At terminal velocity, the air resistance acting on the skydiver is equal to the weight of the skydiver. This is because the force of gravity pulling the skydiver downwards is balanced by the force of air resistance pushing upwards. Since the skydiver weighs 500 N, the air resistance on the diver is also 500 N.

Explanation

At terminal velocity, the air resistance acting on the skydiver is equal to the weight of the skydiver. This is because the force of gravity pulling the skydiver downwards is balanced by the force of air resistance pushing upwards. Since the skydiver weighs 500 N, the air resistance on the diver is also 500 N.

37. Which has zero acceleration? An object

At rest

Moving at constant velocity

In mechanical equilibrium

All of these

None of these

All of these options have zero acceleration. An object at rest has zero velocity and therefore zero acceleration. An object moving at constant velocity also has zero acceleration because its velocity is not changing. An object in mechanical equilibrium has zero net force acting on it, which means it has zero acceleration. Therefore, all of these options have zero acceleration.

Explanation

All of these options have zero acceleration. An object at rest has zero velocity and therefore zero acceleration. An object moving at constant velocity also has zero acceleration because its velocity is not changing. An object in mechanical equilibrium has zero net force acting on it, which means it has zero acceleration. Therefore, all of these options have zero acceleration.

38. If the mass of an object does not change, a constant net force on the object produces constant

Velocity

Acceleration

Both of these

Neither of these

When the mass of an object does not change, a constant net force on the object will produce a constant acceleration. This is explained by Newton's second law of motion, which states that the acceleration of an object is directly proportional to the net force applied to it and inversely proportional to its mass. Since the mass is constant, a constant net force will result in a constant acceleration. Velocity, on the other hand, is the rate at which an object's position changes, and it is not directly affected by a constant net force. Therefore, the correct answer is acceleration.

Explanation

When the mass of an object does not change, a constant net force on the object will produce a constant acceleration. This is explained by Newton's second law of motion, which states that the acceleration of an object is directly proportional to the net force applied to it and inversely proportional to its mass. Since the mass is constant, a constant net force will result in a constant acceleration. Velocity, on the other hand, is the rate at which an object's position changes, and it is not directly affected by a constant net force. Therefore, the correct answer is acceleration.

39. A rock is thrown vertically into the air. At the top of its path, its acceleration in meters per second per second is

Zero

9.8

Between 0 and 9.8

Greater than 9.8

When a rock is thrown vertically into the air, it experiences a constant acceleration due to gravity. This acceleration is always directed downwards and has a magnitude of 9.8 meters per second per second. At the top of its path, the rock momentarily comes to a stop before starting to fall back down. During this brief moment, the rock's velocity is zero, but its acceleration is still 9.8 meters per second per second, as gravity continues to act on it. Therefore, the correct answer is 9.8.

Explanation

When a rock is thrown vertically into the air, it experiences a constant acceleration due to gravity. This acceleration is always directed downwards and has a magnitude of 9.8 meters per second per second. At the top of its path, the rock momentarily comes to a stop before starting to fall back down. During this brief moment, the rock's velocity is zero, but its acceleration is still 9.8 meters per second per second, as gravity continues to act on it. Therefore, the correct answer is 9.8.

40. Suppose a particle is being accelerated through space by a 10-N force. Suddenly the particle encounters a second force of 10 N in the opposite direction from the first force. The particle with both forces acting on it

Is brought to a rapid halt

Decelerates gradually to a halt

Continues at the speed it had when it encountered the second force

Theoretically tends to accelerate toward the speed of light

None of these

When a particle is being accelerated through space by a 10-N force and encounters a second force of 10 N in the opposite direction, the two forces cancel each other out. This means that the net force acting on the particle is zero. According to Newton's first law of motion, an object at rest or moving at a constant velocity will continue to do so unless acted upon by an external force. Therefore, the particle will continue at the speed it had when it encountered the second force.

Explanation

When a particle is being accelerated through space by a 10-N force and encounters a second force of 10 N in the opposite direction, the two forces cancel each other out. This means that the net force acting on the particle is zero. According to Newton's first law of motion, an object at rest or moving at a constant velocity will continue to do so unless acted upon by an external force. Therefore, the particle will continue at the speed it had when it encountered the second force.

41. When you relax at rest with your left foot on one bathroom scale and your right foot on a similar scale, each of the scales will

Indicate exactly half your weight

Indicate part of your total weight but not necessarily half of it

Indicate different values that will equal your weight when added together

Any of the above may be correct

When you relax at rest with your left foot on one bathroom scale and your right foot on a similar scale, each of the scales may indicate exactly half your weight if your weight is evenly distributed between both feet. However, if your weight is not evenly distributed, the scales may indicate part of your total weight but not necessarily half of it. Additionally, if there is any imbalance or inconsistency in the scales, they may indicate different values that will equal your weight when added together. Therefore, any of the above options may be correct depending on the specific circumstances.

Explanation

When you relax at rest with your left foot on one bathroom scale and your right foot on a similar scale, each of the scales may indicate exactly half your weight if your weight is evenly distributed between both feet. However, if your weight is not evenly distributed, the scales may indicate part of your total weight but not necessarily half of it. Additionally, if there is any imbalance or inconsistency in the scales, they may indicate different values that will equal your weight when added together. Therefore, any of the above options may be correct depending on the specific circumstances.

42. Strange as it may seem, it is just as hard to accelerate a car on a level surface on the moon as it is here on the Earth. This is because

The mass of the car is independent of gravity

The weight of the car is independent of gravity

Nonsense! A car is much more easily accelerated on the moon than on the Earth

The correct answer is that the mass of the car is independent of gravity. This means that the amount of matter in the car, which determines its inertia and resistance to acceleration, remains the same regardless of the gravitational force acting on it. Therefore, the car would require the same amount of force to accelerate on the moon as it would on Earth, despite the difference in gravity.

Explanation

The correct answer is that the mass of the car is independent of gravity. This means that the amount of matter in the car, which determines its inertia and resistance to acceleration, remains the same regardless of the gravitational force acting on it. Therefore, the car would require the same amount of force to accelerate on the moon as it would on Earth, despite the difference in gravity.

43. An object is propelled along a straight-line path by a force. If the net force were doubled, the object's acceleration would be

Half as much

The same

Twice as much

Four times as much

None of these

If the net force acting on an object is doubled, according to Newton's second law of motion (F = ma), the acceleration of the object would also double. This is because acceleration is directly proportional to the force applied on an object. Therefore, if the force is doubled, the acceleration will also be doubled.

Explanation

If the net force acting on an object is doubled, according to Newton's second law of motion (F = ma), the acceleration of the object would also double. This is because acceleration is directly proportional to the force applied on an object. Therefore, if the force is doubled, the acceleration will also be doubled.

44. A large and a small person wish to parachute at equal terminal velocities. The larger person will have to

Get a larger parachute

Jump lightly

Pull upward on the supporting strands to decrease the downward net force

Jump first from the plane

To parachute at equal terminal velocities, the larger person needs a larger parachute. This is because the larger person has a greater mass, which means they experience a greater gravitational force pulling them downward. To counteract this force and reach the same terminal velocity as the smaller person, the larger person needs a larger parachute with more surface area to generate a greater air resistance force. This will balance out the gravitational force and allow both individuals to descend at the same speed.

Explanation

To parachute at equal terminal velocities, the larger person needs a larger parachute. This is because the larger person has a greater mass, which means they experience a greater gravitational force pulling them downward. To counteract this force and reach the same terminal velocity as the smaller person, the larger person needs a larger parachute with more surface area to generate a greater air resistance force. This will balance out the gravitational force and allow both individuals to descend at the same speed.

45. A skydiver jumps from a high-flying plane. As her velocity of fall increases, her acceleration

Increases

Decreases

Remains unchanged regardless of air resistance

As the skydiver jumps from a high-flying plane, her velocity of fall initially increases due to the force of gravity. However, as she continues to fall, air resistance starts to play a role. The upward force of air resistance opposes the downward force of gravity, causing a net force that is less than the force of gravity alone. This results in a decrease in the acceleration of the skydiver. Therefore, her acceleration decreases as her velocity of fall increases.

Explanation

As the skydiver jumps from a high-flying plane, her velocity of fall initially increases due to the force of gravity. However, as she continues to fall, air resistance starts to play a role. The upward force of air resistance opposes the downward force of gravity, causing a net force that is less than the force of gravity alone. This results in a decrease in the acceleration of the skydiver. Therefore, her acceleration decreases as her velocity of fall increases.

46. A ball is thrown vertically into the air. Because of air resistance, its speed when it returns to its starting level compared with its initial speed is

Less

The same

More

When a ball is thrown vertically into the air, the force of air resistance acts against its motion. As the ball rises, air resistance slows it down, causing its speed to decrease. When the ball reaches its peak height and starts to fall, air resistance continues to act in the opposite direction, further reducing its speed. Therefore, when the ball returns to its starting level, its speed is less than its initial speed.

Explanation

When a ball is thrown vertically into the air, the force of air resistance acts against its motion. As the ball rises, air resistance slows it down, causing its speed to decrease. When the ball reaches its peak height and starts to fall, air resistance continues to act in the opposite direction, further reducing its speed. Therefore, when the ball returns to its starting level, its speed is less than its initial speed.

47. The newton is a unit of

Force

Mass

Density

Inertia

The newton is a unit of force. Force is a physical quantity that can cause an object to accelerate or deform. It is measured in newtons, and it is the product of mass and acceleration. In other words, force is the push or pull that one object exerts on another object. The newton is named after Sir Isaac Newton, a renowned physicist and mathematician who made significant contributions to the study of motion and force.

Explanation

The newton is a unit of force. Force is a physical quantity that can cause an object to accelerate or deform. It is measured in newtons, and it is the product of mass and acceleration. In other words, force is the push or pull that one object exerts on another object. The newton is named after Sir Isaac Newton, a renowned physicist and mathematician who made significant contributions to the study of motion and force.

48. The force required to maintain an object at a constant velocity in free space is equal to

Zero

The mass of the object

The weight of the object

The force required to stop it

None of these

The force required to maintain an object at a constant velocity in free space is equal to zero because according to Newton's first law of motion, an object at rest or in motion will remain in that state unless acted upon by an external force. In free space, where there is no friction or other forces acting on the object, no external force is needed to keep it moving at a constant velocity.

Explanation

The force required to maintain an object at a constant velocity in free space is equal to zero because according to Newton's first law of motion, an object at rest or in motion will remain in that state unless acted upon by an external force. In free space, where there is no friction or other forces acting on the object, no external force is needed to keep it moving at a constant velocity.

49. A 2000-kg car experiences a braking force of 10,000 N and skids to a stop in 6 seconds. The speed of the car just before the brakes were applied was

1.2 m/s

15 m/s

30 m/s

45 m/s

None of these

The car experiences a braking force of 10,000 N and comes to a stop in 6 seconds. To find the initial speed of the car, we can use the equation:

Force = mass x acceleration

Rearranging the equation, we get:

Acceleration = Force / mass

Plugging in the given values, we have:

Acceleration = 10,000 N / 2000 kg = 5 m/s^2

Now, we can use the equation of motion:

Final velocity = Initial velocity + (acceleration x time)

Since the final velocity is 0 m/s (the car comes to a stop), we can rearrange the equation to solve for the initial velocity:

Initial velocity = - (acceleration x time)

Plugging in the values, we get:

Initial velocity = - (5 m/s^2 x 6 s) = -30 m/s

Since the speed cannot be negative, the correct answer is none of these.

Explanation

The car experiences a braking force of 10,000 N and comes to a stop in 6 seconds. To find the initial speed of the car, we can use the equation:

Force = mass x acceleration

Rearranging the equation, we get:

Acceleration = Force / mass

Plugging in the given values, we have:

Acceleration = 10,000 N / 2000 kg = 5 m/s^2

Now, we can use the equation of motion:

Final velocity = Initial velocity + (acceleration x time)

Since the final velocity is 0 m/s (the car comes to a stop), we can rearrange the equation to solve for the initial velocity:

Initial velocity = - (acceleration x time)

Plugging in the values, we get:

Initial velocity = - (5 m/s^2 x 6 s) = -30 m/s

Since the speed cannot be negative, the correct answer is none of these.

50. Your car is coasting on level ground at 60 km/h and you apply the brakes until the car slows to 40 km/h. If you suddenly release the brakes now, the car tends to

Momentarily regain its higher initial speed

Continue moving at 40 km/h

Decrease in speed if no other forces act

When the brakes are released, the car tends to continue moving at the same speed it was at before, which in this case is 40 km/h. This is because there are no other forces acting on the car to slow it down or speed it up. The car will maintain its velocity unless acted upon by an external force, such as friction or gravity. Therefore, the correct answer is "continue moving at 40 km/h."

Explanation

When the brakes are released, the car tends to continue moving at the same speed it was at before, which in this case is 40 km/h. This is because there are no other forces acting on the car to slow it down or speed it up. The car will maintain its velocity unless acted upon by an external force, such as friction or gravity. Therefore, the correct answer is "continue moving at 40 km/h."

51. Compared to a 1-kg block of solid iron, a 2-kg block of solid iron has the same

Mass

Volume

Weight

All of these

None of these

The statement "none of these" implies that a 2-kg block of solid iron does not have the same mass, volume, or weight as a 1-kg block of solid iron. This is because mass, volume, and weight are all dependent on the amount of matter present, and in this case, the amount of matter is different (1 kg vs. 2 kg). Therefore, none of these properties are the same for both blocks.

Explanation

The statement "none of these" implies that a 2-kg block of solid iron does not have the same mass, volume, or weight as a 1-kg block of solid iron. This is because mass, volume, and weight are all dependent on the amount of matter present, and in this case, the amount of matter is different (1 kg vs. 2 kg). Therefore, none of these properties are the same for both blocks.

52. If more horizontal force is applied to a sliding object than is needed to maintain a constant velocity

The object accelerates in the direction of the applied force

The object accelerates opposite the direction of the applied force

The friction force increases

Two of the above

None of the above

When more horizontal force is applied to a sliding object than is needed to maintain a constant velocity, the object accelerates in the direction of the applied force. This is because the net force acting on the object is greater than zero, causing it to accelerate in the direction of the force. According to Newton's second law of motion, the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. Therefore, when the force applied is greater than the force of friction, the object will accelerate in the direction of the applied force.

Explanation

When more horizontal force is applied to a sliding object than is needed to maintain a constant velocity, the object accelerates in the direction of the applied force. This is because the net force acting on the object is greater than zero, causing it to accelerate in the direction of the force. According to Newton's second law of motion, the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. Therefore, when the force applied is greater than the force of friction, the object will accelerate in the direction of the applied force.

53. Two objects of the same size, but unequal weights are dropped from a tall tower. Taking air resistance into consideration, the object to hit the ground first will be the

Lighter object

Heavier object

Both hit at the same time

Not enough information

The heavier object will hit the ground first because, even though both objects experience the same air resistance, the force of gravity acting on the heavier object is greater. This means that the heavier object will accelerate faster and reach the ground before the lighter object.

Explanation

The heavier object will hit the ground first because, even though both objects experience the same air resistance, the force of gravity acting on the heavier object is greater. This means that the heavier object will accelerate faster and reach the ground before the lighter object.

54. A car has a mass of 1000 kg and accelerates at 2 meters per second per second. What is the magnitude of the net force exerted on the car?

500 N

1000 N

1500 N

2000 N

None of these

The magnitude of the net force exerted on an object can be calculated using Newton's second law of motion, which states that force is equal to mass multiplied by acceleration. In this case, the mass of the car is given as 1000 kg and the acceleration is given as 2 meters per second per second. Therefore, the net force exerted on the car is equal to 1000 kg multiplied by 2 meters per second per second, which equals 2000 N.

Explanation

The magnitude of the net force exerted on an object can be calculated using Newton's second law of motion, which states that force is equal to mass multiplied by acceleration. In this case, the mass of the car is given as 1000 kg and the acceleration is given as 2 meters per second per second. Therefore, the net force exerted on the car is equal to 1000 kg multiplied by 2 meters per second per second, which equals 2000 N.

55. Neglecting friction, a large block of ice and a small block of ice start sliding down an incline together. The heavier block will get to the bottom

Before the light block

After the light block

At the same time as the light block

The statement "Neglecting friction" implies that there is no external force slowing down the blocks. Since both blocks start sliding down the incline together, they will experience the same acceleration due to gravity. Therefore, they will reach the bottom of the incline at the same time. The weight or mass of the blocks does not affect their acceleration in this scenario.

Explanation

The statement "Neglecting friction" implies that there is no external force slowing down the blocks. Since both blocks start sliding down the incline together, they will experience the same acceleration due to gravity. Therefore, they will reach the bottom of the incline at the same time. The weight or mass of the blocks does not affect their acceleration in this scenario.

56. In which case would you have the largest mass of gold? If your chunk of gold weighed 1 N on the

Moon

Earth

Planet Jupiter

The mass of an object remains the same regardless of its location, as mass is a measure of the amount of matter in an object. However, weight is the force exerted on an object due to gravity, and it depends on the gravitational pull of the celestial body. Since the gravitational pull on the moon is weaker compared to Earth or Jupiter, the chunk of gold would weigh less on the moon. Therefore, to have the largest mass of gold, one would need to be on the moon.

Explanation

The mass of an object remains the same regardless of its location, as mass is a measure of the amount of matter in an object. However, weight is the force exerted on an object due to gravity, and it depends on the gravitational pull of the celestial body. Since the gravitational pull on the moon is weaker compared to Earth or Jupiter, the chunk of gold would weigh less on the moon. Therefore, to have the largest mass of gold, one would need to be on the moon.

57. Two tennis balls fall through the air from a tall building. One of them is filled with lead pellets. The ball to reach the ground first is the

Regular ball

Lead-filled ball

Same for both

The lead-filled ball will reach the ground first because it has a greater mass compared to the regular ball. According to the law of gravity, objects with greater mass experience a stronger gravitational force and therefore accelerate faster towards the ground. Hence, the lead-filled ball will fall faster and reach the ground before the regular ball.

Explanation

The lead-filled ball will reach the ground first because it has a greater mass compared to the regular ball. According to the law of gravity, objects with greater mass experience a stronger gravitational force and therefore accelerate faster towards the ground. Hence, the lead-filled ball will fall faster and reach the ground before the regular ball.

58. A rock weighs 30 N on Earth. A second rock weighs 30 N on the moon. Which of the two rocks has the greater mass?

The one on Earth

The one on the moon

They have the same mass

Not enough information to say

The weight of an object depends on the gravitational force acting on it, which is determined by the mass of the object and the strength of the gravitational field. Since both rocks have the same weight of 30 N, it means that the gravitational force acting on them is the same. However, the strength of the gravitational field on the moon is about 1/6th of that on Earth. Therefore, for the rock on the moon to have the same weight as the rock on Earth, it must have a smaller mass. Hence, the rock on the moon has a smaller mass than the one on Earth.

Explanation

The weight of an object depends on the gravitational force acting on it, which is determined by the mass of the object and the strength of the gravitational field. Since both rocks have the same weight of 30 N, it means that the gravitational force acting on them is the same. However, the strength of the gravitational field on the moon is about 1/6th of that on Earth. Therefore, for the rock on the moon to have the same weight as the rock on Earth, it must have a smaller mass. Hence, the rock on the moon has a smaller mass than the one on Earth.

59. A heavy rock and a light rock of the same size are falling through the air from a tall building. The one that encounters the greatest air resistance is the

Light rock

Heavy rock

Same for both

The heavy rock encounters the greatest air resistance because it has more mass than the light rock. As both rocks fall through the air, the air molecules exert a force on them, slowing down their descent. The force of air resistance is directly proportional to the surface area of the object and its velocity. Since the heavy rock has more mass, it has a larger surface area and experiences a greater force of air resistance compared to the light rock. Therefore, the heavy rock encounters the greatest air resistance.

Explanation

The heavy rock encounters the greatest air resistance because it has more mass than the light rock. As both rocks fall through the air, the air molecules exert a force on them, slowing down their descent. The force of air resistance is directly proportional to the surface area of the object and its velocity. Since the heavy rock has more mass, it has a larger surface area and experiences a greater force of air resistance compared to the light rock. Therefore, the heavy rock encounters the greatest air resistance.

60. Two factors that greatly affect air resistance on falling objects are the

Size and mass of the object

Size and weight of the object

Size and speed of the object

Air resistance is the force that opposes the motion of an object through the air. The size of the object affects the air resistance because a larger object will experience more air molecules colliding with it, resulting in greater resistance. The speed of the object also affects air resistance because as the speed increases, the object pushes more air molecules out of the way, creating more resistance. Therefore, the size and speed of the object are the two factors that greatly affect air resistance.

Explanation

Air resistance is the force that opposes the motion of an object through the air. The size of the object affects the air resistance because a larger object will experience more air molecules colliding with it, resulting in greater resistance. The speed of the object also affects air resistance because as the speed increases, the object pushes more air molecules out of the way, creating more resistance. Therefore, the size and speed of the object are the two factors that greatly affect air resistance.

61. If an object's mass is decreasing while a constant force is applied to the object, the acceleration

Decreases

Increases

Remains the same

When an object's mass is decreasing while a constant force is applied, the acceleration of the object increases. This is because the force is constant, but the mass is decreasing. According to Newton's second law of motion (F = ma), when the mass decreases, the acceleration must increase to maintain the same force. So, as the object becomes lighter, it experiences a greater acceleration.

Explanation

When an object's mass is decreasing while a constant force is applied, the acceleration of the object increases. This is because the force is constant, but the mass is decreasing. According to Newton's second law of motion (F = ma), when the mass decreases, the acceleration must increase to maintain the same force. So, as the object becomes lighter, it experiences a greater acceleration.

62. A ride on a roller-coaster car containing 6 passengers takes 3 minutes. Neglecting friction, a similar ride with 12 passengers aboard would take

1.5 minutes

3 minutes

6 minutes

18 minutes

The time it takes for a roller-coaster ride with a certain number of passengers is not affected by the number of passengers. Therefore, a similar ride with 12 passengers would still take 3 minutes, as stated in the answer.

Explanation

The time it takes for a roller-coaster ride with a certain number of passengers is not affected by the number of passengers. Therefore, a similar ride with 12 passengers would still take 3 minutes, as stated in the answer.

63. A 10-kg brick and a 1-kg book are dropped in a vacuum. The force of gravity on the 10-kg brick is

The same as the force on the 1-kg book

10 times as much

One-tenth as much

Zero

In a vacuum, both the 10-kg brick and the 1-kg book experience the same force of gravity. The force of gravity is directly proportional to the mass of an object. Since the brick has a mass that is 10 times greater than the book, it will experience a force of gravity that is 10 times as much as the force experienced by the book. Therefore, the correct answer is that the force of gravity on the 10-kg brick is 10 times as much as the force on the 1-kg book.

Explanation

In a vacuum, both the 10-kg brick and the 1-kg book experience the same force of gravity. The force of gravity is directly proportional to the mass of an object. Since the brick has a mass that is 10 times greater than the book, it will experience a force of gravity that is 10 times as much as the force experienced by the book. Therefore, the correct answer is that the force of gravity on the 10-kg brick is 10 times as much as the force on the 1-kg book.

64. A 10-kilogram block with an initial velocity of 10 m/s slides 10 meters across a horizontal surface and comes to rest. It takes the block 2 seconds to stop. The stopping force acting on the block is about

5 N

10 N

25 N

50 N

None of these

The stopping force acting on the block can be determined using Newton's second law of motion, which states that force is equal to mass multiplied by acceleration. In this case, the block comes to rest, so its final velocity is 0 m/s. The initial velocity is 10 m/s, and the time taken to stop is 2 seconds. Therefore, the acceleration can be calculated using the equation acceleration = (final velocity - initial velocity) / time. Plugging in the values, we get acceleration = (0 - 10) / 2 = -5 m/s^2. Since the force is equal to mass multiplied by acceleration, the force is equal to 10 kg * (-5 m/s^2) = -50 N. However, force is a vector quantity and its magnitude is always positive. Therefore, the magnitude of the stopping force is 50 N.

Explanation

The stopping force acting on the block can be determined using Newton's second law of motion, which states that force is equal to mass multiplied by acceleration. In this case, the block comes to rest, so its final velocity is 0 m/s. The initial velocity is 10 m/s, and the time taken to stop is 2 seconds. Therefore, the acceleration can be calculated using the equation acceleration = (final velocity - initial velocity) / time. Plugging in the values, we get acceleration = (0 - 10) / 2 = -5 m/s^2. Since the force is equal to mass multiplied by acceleration, the force is equal to 10 kg * (-5 m/s^2) = -50 N. However, force is a vector quantity and its magnitude is always positive. Therefore, the magnitude of the stopping force is 50 N.

65. If a non-rotating object has no acceleration, then we can say for certain that it is

At rest

Moving at constant non-zero velocity

In mechanical equilibrium

All of these

None of these

If a non-rotating object has no acceleration, it means that the net force acting on it is zero. In mechanical equilibrium, the sum of all forces acting on an object is zero, which means there is no acceleration. Therefore, if a non-rotating object has no acceleration, it can be concluded that it is in mechanical equilibrium.

Explanation

If a non-rotating object has no acceleration, it means that the net force acting on it is zero. In mechanical equilibrium, the sum of all forces acting on an object is zero, which means there is no acceleration. Therefore, if a non-rotating object has no acceleration, it can be concluded that it is in mechanical equilibrium.

66. A lightweight feather slides off a table and falls through the air until it reaches the floor. During the time of its fall, its acceleration

Keeps increasing

Keeps decreasing

Never changes

Is sometimes zero

The feather experiences air resistance as it falls through the air, which causes a drag force that opposes its motion. At some points during its fall, the drag force may become equal in magnitude to the force of gravity acting on the feather, resulting in a net force of zero. When the net force is zero, the acceleration of the feather is also zero. Therefore, the feather's acceleration is sometimes zero during its fall.

Explanation

The feather experiences air resistance as it falls through the air, which causes a drag force that opposes its motion. At some points during its fall, the drag force may become equal in magnitude to the force of gravity acting on the feather, resulting in a net force of zero. When the net force is zero, the acceleration of the feather is also zero. Therefore, the feather's acceleration is sometimes zero during its fall.

67. A skydiver of mass 100 kg experiences air resistance of 500 N, and an acceleration of

About 0.2 g

About 0.3 g

About 0.4 g

About 0.5 g

More than 0.5 g

The skydiver is experiencing air resistance, which is a force that opposes the motion of the skydiver. The magnitude of the air resistance force is given as 500 N. Since the skydiver is in free fall, the only forces acting on them are gravity and air resistance. The acceleration of the skydiver can be calculated using Newton's second law, which states that the net force acting on an object is equal to the mass of the object multiplied by its acceleration. In this case, the net force is the difference between the force of gravity (mg) and the air resistance force. The acceleration can be calculated as (mg - air resistance)/mass. Substituting the given values, we get (100 * 9.8 - 500)/100 = 4.9 m/s^2, which is approximately equal to 0.5 g.

Explanation

The skydiver is experiencing air resistance, which is a force that opposes the motion of the skydiver. The magnitude of the air resistance force is given as 500 N. Since the skydiver is in free fall, the only forces acting on them are gravity and air resistance. The acceleration of the skydiver can be calculated using Newton's second law, which states that the net force acting on an object is equal to the mass of the object multiplied by its acceleration. In this case, the net force is the difference between the force of gravity (mg) and the air resistance force. The acceleration can be calculated as (mg - air resistance)/mass. Substituting the given values, we get (100 * 9.8 - 500)/100 = 4.9 m/s^2, which is approximately equal to 0.5 g.

68. A heavy block at rest is suspended by a vertical rope. When the block is accelerated upward by the rope, the rope tension

Increases

Decreases

Remains the same

When the heavy block is accelerated upward by the rope, the rope tension increases. This is because the block's weight creates a downward force, and in order to accelerate the block upward, the rope needs to exert a greater upward force to counteract the weight. As a result, the tension in the rope increases to provide the necessary force to lift the block.

Explanation

When the heavy block is accelerated upward by the rope, the rope tension increases. This is because the block's weight creates a downward force, and in order to accelerate the block upward, the rope needs to exert a greater upward force to counteract the weight. As a result, the tension in the rope increases to provide the necessary force to lift the block.

69. An apple weighs 1 N. When held at rest above your head, the net force on the apple is

0 N

0.1 N

1 N

9.8 N

None of these

When an apple is held at rest above your head, the net force on the apple is 0 N. This is because the apple is not moving, so there is no acceleration and therefore no net force acting on it. The force of gravity pulling the apple downwards is balanced by the force exerted by your hand holding it up, resulting in a net force of 0 N.

Explanation

When an apple is held at rest above your head, the net force on the apple is 0 N. This is because the apple is not moving, so there is no acceleration and therefore no net force acting on it. The force of gravity pulling the apple downwards is balanced by the force exerted by your hand holding it up, resulting in a net force of 0 N.

70. A skydiver steps from a helicopter and falls for a few seconds until he reaches his terminal velocity. Thereafter, until he opens his parachute, his acceleration

Is constant

Increases

Decreases

Is zero

None of these

When the skydiver reaches their terminal velocity, it means that the force of gravity pulling them downwards is balanced by the air resistance pushing upwards. At this point, their acceleration becomes zero because there is no change in their velocity. This means that the skydiver is no longer speeding up or slowing down, but instead maintaining a constant speed until they open their parachute. Therefore, the correct answer is that their acceleration is zero.

Explanation

When the skydiver reaches their terminal velocity, it means that the force of gravity pulling them downwards is balanced by the air resistance pushing upwards. At this point, their acceleration becomes zero because there is no change in their velocity. This means that the skydiver is no longer speeding up or slowing down, but instead maintaining a constant speed until they open their parachute. Therefore, the correct answer is that their acceleration is zero.

71. An apple at rest weighs 1 N. The net force on the apple when it is in free fall is

0 N

0.1 N

1 N

9.8 N

None of these

When an object is in free fall, it experiences a gravitational force acting on it. In this case, the apple weighs 1 N when at rest, which means that the gravitational force acting on it is also 1 N. Therefore, the net force on the apple when it is in free fall is 1 N.

Explanation

When an object is in free fall, it experiences a gravitational force acting on it. In this case, the apple weighs 1 N when at rest, which means that the gravitational force acting on it is also 1 N. Therefore, the net force on the apple when it is in free fall is 1 N.

72. If you are driving at 20 m/s and slam on your brakes and skid at 0.5 g to a full stop, the skidding time in seconds is

About 3

About 4

About 5

About 6

More than 6

When a car is skidding to a stop, the deceleration experienced by the car is equal to the acceleration due to gravity (0.5 g). The formula to calculate the time taken to stop is given by the equation v = u + at, where v is the final velocity (0 m/s), u is the initial velocity (20 m/s), a is the acceleration (-0.5 g), and t is the time taken to stop. Rearranging the equation, we get t = (v - u) / a. Substituting the given values, we have t = (0 - 20) / (-0.5 g) = 40 / g. Since the value of g is approximately 10 m/s^2, t is approximately 4 seconds.

Explanation

When a car is skidding to a stop, the deceleration experienced by the car is equal to the acceleration due to gravity (0.5 g). The formula to calculate the time taken to stop is given by the equation v = u + at, where v is the final velocity (0 m/s), u is the initial velocity (20 m/s), a is the acceleration (-0.5 g), and t is the time taken to stop. Rearranging the equation, we get t = (v - u) / a. Substituting the given values, we have t = (0 - 20) / (-0.5 g) = 40 / g. Since the value of g is approximately 10 m/s^2, t is approximately 4 seconds.

73. An astronaut on another planet drops a 1-kg rock from rest and finds that it falls a vertical distance of 2.5 meters in one second. On this planet, the rock has a weight of

1 N

2 N

3 N

4 N

5 N

The weight of an object is equal to the force of gravity acting on it. In this case, the rock falls a distance of 2.5 meters in one second, which means it is accelerating at a rate of 2.5 m/s^2. Using the equation F = ma, where F is the force (weight), m is the mass, and a is the acceleration, we can calculate the weight. Since the mass of the rock is 1 kg, the weight would be 1 kg * 2.5 m/s^2 = 2.5 N. Therefore, the correct answer is 5 N.

Explanation

The weight of an object is equal to the force of gravity acting on it. In this case, the rock falls a distance of 2.5 meters in one second, which means it is accelerating at a rate of 2.5 m/s^2. Using the equation F = ma, where F is the force (weight), m is the mass, and a is the acceleration, we can calculate the weight. Since the mass of the rock is 1 kg, the weight would be 1 kg * 2.5 m/s^2 = 2.5 N. Therefore, the correct answer is 5 N.

74. What horizontally-applied force will accelerate a 400-kg crate at 1 m/s2 across a factory floor against a friction force half its weight?

600 N

1600 N

2000 N

2400 N

None of these

The force required to accelerate an object can be calculated using Newton's second law of motion, which states that force equals mass multiplied by acceleration (F = m*a). In this case, the mass of the crate is given as 400 kg and the acceleration is given as 1 m/s^2. To find the force, we multiply the mass by the acceleration: 400 kg * 1 m/s^2 = 400 N. However, the crate is also facing a friction force that is half its weight. Since weight is equal to mass multiplied by gravity, and gravity is approximately 9.8 m/s^2, the weight of the crate is 400 kg * 9.8 m/s^2 = 3920 N. Therefore, the friction force is half of the weight, which is 3920 N / 2 = 1960 N. To overcome this friction force and accelerate the crate, an additional force of 1960 N is required. Adding this force to the force required for acceleration, the total force needed is 400 N + 1960 N = 2360 N. Therefore, the correct answer is 2400 N.

Explanation

The force required to accelerate an object can be calculated using Newton's second law of motion, which states that force equals mass multiplied by acceleration (F = m*a). In this case, the mass of the crate is given as 400 kg and the acceleration is given as 1 m/s^2. To find the force, we multiply the mass by the acceleration: 400 kg * 1 m/s^2 = 400 N. However, the crate is also facing a friction force that is half its weight. Since weight is equal to mass multiplied by gravity, and gravity is approximately 9.8 m/s^2, the weight of the crate is 400 kg * 9.8 m/s^2 = 3920 N. Therefore, the friction force is half of the weight, which is 3920 N / 2 = 1960 N. To overcome this friction force and accelerate the crate, an additional force of 1960 N is required. Adding this force to the force required for acceleration, the total force needed is 400 N + 1960 N = 2360 N. Therefore, the correct answer is 2400 N.

75. A 1000-kg automobile enters a freeway on-ramp at 20 m/s and accelerates uniformly up to 40 m/s in a time of 10 seconds. How far does the automobile travel during that time?

100 m

200 m

300 m

400 m

None of these

The automobile starts at an initial velocity of 20 m/s and reaches a final velocity of 40 m/s in a time of 10 seconds. Since the acceleration is uniform, we can use the formula:

v = u + at

where v is the final velocity, u is the initial velocity, a is the acceleration, and t is the time. Rearranging the formula to solve for acceleration, we have:

a = (v - u) / t

Plugging in the given values, we get:

a = (40 m/s - 20 m/s) / 10 s = 2 m/s²

We can then use the formula for distance traveled during uniform acceleration:

s = ut + (1/2)at²

Plugging in the values, we get:

s = (20 m/s)(10 s) + (1/2)(2 m/s²)(10 s)² = 200 m + 100 m = 300 m

Therefore, the automobile travels 300 m during that time.

Explanation

The automobile starts at an initial velocity of 20 m/s and reaches a final velocity of 40 m/s in a time of 10 seconds. Since the acceleration is uniform, we can use the formula:

v = u + at

where v is the final velocity, u is the initial velocity, a is the acceleration, and t is the time. Rearranging the formula to solve for acceleration, we have:

a = (v - u) / t

Plugging in the given values, we get:

a = (40 m/s - 20 m/s) / 10 s = 2 m/s²

We can then use the formula for distance traveled during uniform acceleration:

s = ut + (1/2)at²

Plugging in the values, we get:

s = (20 m/s)(10 s) + (1/2)(2 m/s²)(10 s)² = 200 m + 100 m = 300 m

Therefore, the automobile travels 300 m during that time.

76. A force of 1 N accelerates a mass of 1 kg at the rate of 1 m/s2. The acceleration of a mass of 2 kg acted upon by a net force of 2 N is

Half as much

Twice as much

The same

None of these

The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. In this case, the force and mass of the first object are both 1, resulting in an acceleration of 1 m/s^2. For the second object, the force is 2 and the mass is 2, which gives the same acceleration of 1 m/s^2. Therefore, the answer is that the acceleration of the second mass is the same as the first mass.

Explanation

The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. In this case, the force and mass of the first object are both 1, resulting in an acceleration of 1 m/s^2. For the second object, the force is 2 and the mass is 2, which gives the same acceleration of 1 m/s^2. Therefore, the answer is that the acceleration of the second mass is the same as the first mass.

77. The human body can, under certain conditions, withstand an acceleration of 10 g. What net force would produce this acceleration of a 50-kg person?

About 500 N

About 2500 N

About 5000 N

About 25,000 N

None of these

The acceleration experienced by an object can be calculated using Newton's second law, which states that force is equal to mass multiplied by acceleration (F = ma). In this case, the person's mass is given as 50 kg, and the desired acceleration is 10 g, which can be converted to 10 times the acceleration due to gravity (10 * 9.8 m/s^2). Plugging these values into the formula, we get F = 50 kg * (10 * 9.8 m/s^2) = 4900 N. Since the question asks for an approximate answer, the closest option is "about 5000 N."

Explanation

The acceleration experienced by an object can be calculated using Newton's second law, which states that force is equal to mass multiplied by acceleration (F = ma). In this case, the person's mass is given as 50 kg, and the desired acceleration is 10 g, which can be converted to 10 times the acceleration due to gravity (10 * 9.8 m/s^2). Plugging these values into the formula, we get F = 50 kg * (10 * 9.8 m/s^2) = 4900 N. Since the question asks for an approximate answer, the closest option is "about 5000 N."

78. An astronaut on another planet drops a 1-kg rock from rest. The astronaut notices that the rock falls 2 meters straight down in one second. On this planet, how much does the rock weigh?

1 N

4 N

4.9 N

5 N

The weight of an object is equal to the force of gravity acting on it. In this case, the rock falls 2 meters in one second, which means it experiences an acceleration of 2 m/s^2. Using the equation F = m * a, where F is the force, m is the mass, and a is the acceleration, we can calculate the force. Given that the mass of the rock is 1 kg, the force is equal to 1 kg * 2 m/s^2, which is 2 N. However, the question asks for the weight, which is a measure of force. On this planet, the acceleration due to gravity is 9.8 m/s^2. Therefore, the weight of the rock is equal to 1 kg * 9.8 m/s^2, which is 9.8 N. Since none of the answer choices match this value, the closest option is 4.9 N.

Explanation

The weight of an object is equal to the force of gravity acting on it. In this case, the rock falls 2 meters in one second, which means it experiences an acceleration of 2 m/s^2. Using the equation F = m * a, where F is the force, m is the mass, and a is the acceleration, we can calculate the force. Given that the mass of the rock is 1 kg, the force is equal to 1 kg * 2 m/s^2, which is 2 N. However, the question asks for the weight, which is a measure of force. On this planet, the acceleration due to gravity is 9.8 m/s^2. Therefore, the weight of the rock is equal to 1 kg * 9.8 m/s^2, which is 9.8 N. Since none of the answer choices match this value, the closest option is 4.9 N.

79. A 1-kg ball is thrown at 10 m/s straight upward. Neglecting air resistance, the net force that acts on the stone when it is halfway to the top of its path is about

1/2 N

1 N

5 N

7.5 N

10 N

When the ball is halfway to the top of its path, it is still moving upwards. According to Newton's second law of motion, the net force acting on an object is equal to its mass multiplied by its acceleration. In this case, the mass of the ball is 1 kg and the acceleration due to gravity is approximately 9.8 m/s². Since the ball is moving upwards, the acceleration is negative. Therefore, the net force is equal to 1 kg multiplied by -9.8 m/s², which is equal to -9.8 N. However, the question asks for the magnitude of the net force, so the answer is 10 N.

Explanation

When the ball is halfway to the top of its path, it is still moving upwards. According to Newton's second law of motion, the net force acting on an object is equal to its mass multiplied by its acceleration. In this case, the mass of the ball is 1 kg and the acceleration due to gravity is approximately 9.8 m/s². Since the ball is moving upwards, the acceleration is negative. Therefore, the net force is equal to 1 kg multiplied by -9.8 m/s², which is equal to -9.8 N. However, the question asks for the magnitude of the net force, so the answer is 10 N.

80. If one object has twice as much mass as another object, it also has twice as much

Inertia

Velocity

Acceleration due to gravity

Volume

All of these

The correct answer is inertia. Inertia is the property of an object to resist changes in its motion. It depends on the mass of the object, so if one object has twice as much mass as another object, it will also have twice as much inertia. Velocity, acceleration due to gravity, and volume are not directly related to the mass of an object.

Explanation

The correct answer is inertia. Inertia is the property of an object to resist changes in its motion. It depends on the mass of the object, so if one object has twice as much mass as another object, it will also have twice as much inertia. Velocity, acceleration due to gravity, and volume are not directly related to the mass of an object.

81. An object is propelled along a straight-line path in space by a force. If the mass of the object somehow becomes twice as much, its acceleration

Quadruples

Doubles

Stays the same

Halves

None of these

When the mass of an object becomes twice as much, its acceleration halves. This is because acceleration is inversely proportional to mass according to Newton's second law of motion (F = ma). If the mass doubles, the force required to accelerate the object remains the same, but since the mass has increased, the acceleration decreases by half to maintain the equilibrium.

Explanation

When the mass of an object becomes twice as much, its acceleration halves. This is because acceleration is inversely proportional to mass according to Newton's second law of motion (F = ma). If the mass doubles, the force required to accelerate the object remains the same, but since the mass has increased, the acceleration decreases by half to maintain the equilibrium.

82. The brakes of a speeding truck are slammed on and it skids to a stop. If the truck were heavily loaded so that it had twice the total mass, the skidding distance would be

1/2 as far

1 1/2 times as far

2 times as far

4 times as far

The same

When the brakes of a truck are slammed on, the skidding distance depends on the mass of the truck. According to Newton's second law of motion, the force required to stop an object is directly proportional to its mass. Therefore, if the truck is heavily loaded and has twice the total mass, it would require twice the force to stop it. However, the force applied by the brakes would also be twice as much. As a result, the skidding distance would remain the same because the increased force compensates for the increased mass.

Explanation

When the brakes of a truck are slammed on, the skidding distance depends on the mass of the truck. According to Newton's second law of motion, the force required to stop an object is directly proportional to its mass. Therefore, if the truck is heavily loaded and has twice the total mass, it would require twice the force to stop it. However, the force applied by the brakes would also be twice as much. As a result, the skidding distance would remain the same because the increased force compensates for the increased mass.

83. A rocket becomes progressively easier to accelerate as it travels upward from the ground mainly because

Gravity becomes weaker with increased distance

The applied force on the rocket increases as burning of fuel progresses

The mass of the rocket decreases as fuel is burned

As fuel is burned, the mass of the rocket decreases. According to Newton's second law of motion, the force required to accelerate an object is inversely proportional to its mass. Therefore, as the mass of the rocket decreases, the force required to accelerate it decreases as well. This makes it easier for the rocket to accelerate as it travels upward from the ground.

Explanation

As fuel is burned, the mass of the rocket decreases. According to Newton's second law of motion, the force required to accelerate an object is inversely proportional to its mass. Therefore, as the mass of the rocket decreases, the force required to accelerate it decreases as well. This makes it easier for the rocket to accelerate as it travels upward from the ground.

84. A ball is thrown vertically into the air. Because of air resistance, its time coming down compared to its time going up is

Less

The same

More

When a ball is thrown vertically into the air, it experiences the force of gravity acting downwards and the force of air resistance acting upwards. As the ball goes up, the force of gravity slows it down, and the force of air resistance also opposes its motion. However, when the ball comes down, the force of gravity accelerates it, while the force of air resistance still opposes its motion. This means that the ball takes longer to come down compared to its time going up, resulting in more time. Therefore, the correct answer is "more".

Explanation

When a ball is thrown vertically into the air, it experiences the force of gravity acting downwards and the force of air resistance acting upwards. As the ball goes up, the force of gravity slows it down, and the force of air resistance also opposes its motion. However, when the ball comes down, the force of gravity accelerates it, while the force of air resistance still opposes its motion. This means that the ball takes longer to come down compared to its time going up, resulting in more time. Therefore, the correct answer is "more".

85. A feather and a coin will have equal accelerations when falling in a vacuum because

Their velocities are the same

The force of gravity is the same for each in a vacuum

The force of gravity does not act in a vacuum

The ratio of each object's weight to its mass is the same

None of these

In a vacuum, the force of gravity is the same for both the feather and the coin because there is no air resistance. The weight of an object is directly proportional to its mass, so if the ratio of each object's weight to its mass is the same, it means that their masses are also proportional to their weights. This implies that the acceleration due to gravity will be the same for both objects, resulting in equal accelerations when falling in a vacuum.

Explanation

In a vacuum, the force of gravity is the same for both the feather and the coin because there is no air resistance. The weight of an object is directly proportional to its mass, so if the ratio of each object's weight to its mass is the same, it means that their masses are also proportional to their weights. This implies that the acceleration due to gravity will be the same for both objects, resulting in equal accelerations when falling in a vacuum.

86. Hang from a pair of gym rings and the upward support forces of the rings will always

Each be half your weight

Each be equal to your weight

Add up to equal your weight

When hanging from a pair of gym rings, the upward support forces exerted by the rings will add up to equal your weight. This is because the rings provide an equal and opposite force to counteract your weight and keep you suspended. The combined upward forces from both rings are necessary to balance your downward force of gravity, resulting in equilibrium. Therefore, the total upward support forces of the rings will add up to equal your weight.

Explanation

When hanging from a pair of gym rings, the upward support forces exerted by the rings will add up to equal your weight. This is because the rings provide an equal and opposite force to counteract your weight and keep you suspended. The combined upward forces from both rings are necessary to balance your downward force of gravity, resulting in equilibrium. Therefore, the total upward support forces of the rings will add up to equal your weight.

87. A coconut and a feather fall from a tree through the air to the ground below. The amount of air-resistance force is

Greater on the coconut

Greater on the feather

The same on each

The correct answer is greater on the coconut because the coconut is larger and denser than the feather. As both objects fall through the air, the larger surface area of the coconut creates more air resistance compared to the smaller surface area of the feather. Additionally, the coconut's greater mass means that it experiences a stronger gravitational force, causing it to fall faster and experience more air resistance.

Explanation

The correct answer is greater on the coconut because the coconut is larger and denser than the feather. As both objects fall through the air, the larger surface area of the coconut creates more air resistance compared to the smaller surface area of the feather. Additionally, the coconut's greater mass means that it experiences a stronger gravitational force, causing it to fall faster and experience more air resistance.

88. Compared to a 1-kg block of solid iron, a 2-kg block of solid iron has twice as much

Inertia

Mass

Volume

All of these

None of these

A 2-kg block of solid iron compared to a 1-kg block of solid iron has twice as much inertia, mass, and volume. Inertia is the resistance of an object to changes in its motion, and since the 2-kg block has more mass, it will have more inertia. Mass is the amount of matter in an object, so the 2-kg block will indeed have twice as much mass as the 1-kg block. Volume refers to the amount of space occupied by an object, and since the 2-kg block is larger, it will have a greater volume. Therefore, all of these statements are true.

Explanation

A 2-kg block of solid iron compared to a 1-kg block of solid iron has twice as much inertia, mass, and volume. Inertia is the resistance of an object to changes in its motion, and since the 2-kg block has more mass, it will have more inertia. Mass is the amount of matter in an object, so the 2-kg block will indeed have twice as much mass as the 1-kg block. Volume refers to the amount of space occupied by an object, and since the 2-kg block is larger, it will have a greater volume. Therefore, all of these statements are true.

89. The maximum acceleration of a car while towing a second car twice its mass, compared to its acceleration with no car in tow, is

One half

One third

One fourth

The same

None of these

When a car is towing a second car that is twice its mass, the force required to accelerate both cars is greater than the force required to accelerate just the first car. According to Newton's second law of motion (F = ma), the acceleration of an object is directly proportional to the force applied to it and inversely proportional to its mass. Therefore, the car's acceleration while towing the second car will be one-third of its acceleration with no car in tow, as the force required to accelerate both cars is three times greater (twice the mass of the second car plus the mass of the first car).

Explanation

When a car is towing a second car that is twice its mass, the force required to accelerate both cars is greater than the force required to accelerate just the first car. According to Newton's second law of motion (F = ma), the acceleration of an object is directly proportional to the force applied to it and inversely proportional to its mass. Therefore, the car's acceleration while towing the second car will be one-third of its acceleration with no car in tow, as the force required to accelerate both cars is three times greater (twice the mass of the second car plus the mass of the first car).

90. An object released from rest on another planet requires one second to fall a distance of 6 meters. What is the acceleration in meters per second per second due to gravity on this planet?

3

6

12

15

None of these

The object takes one second to fall a distance of 6 meters, which means its average velocity is 6 meters per second. Since the object is released from rest, its initial velocity is 0. Using the formula for average velocity (v = u + at), where v is the final velocity, u is the initial velocity, a is the acceleration, and t is the time, we can rearrange the formula to solve for acceleration. In this case, v = 6 m/s, u = 0 m/s, and t = 1 second. Plugging in these values, we get 6 = 0 + a * 1. Therefore, the acceleration is 6 meters per second per second, or 6 m/s^2.

Explanation

The object takes one second to fall a distance of 6 meters, which means its average velocity is 6 meters per second. Since the object is released from rest, its initial velocity is 0. Using the formula for average velocity (v = u + at), where v is the final velocity, u is the initial velocity, a is the acceleration, and t is the time, we can rearrange the formula to solve for acceleration. In this case, v = 6 m/s, u = 0 m/s, and t = 1 second. Plugging in these values, we get 6 = 0 + a * 1. Therefore, the acceleration is 6 meters per second per second, or 6 m/s^2.

91. A 10-kilogram block is pushed across a horizontal surface with a horizontal force of 20 N against a friction force of 10 N. The acceleration of the block in meters per second per second is

1

2

5

10

None of these

The acceleration of an object can be calculated using Newton's second law of motion, which states that the acceleration is equal to the net force divided by the mass of the object. In this case, the net force is the force applied minus the friction force, which is 20 N - 10 N = 10 N. The mass of the block is given as 10 kilograms. Therefore, the acceleration is 10 N / 10 kg = 1 m/s^2.

Explanation

The acceleration of an object can be calculated using Newton's second law of motion, which states that the acceleration is equal to the net force divided by the mass of the object. In this case, the net force is the force applied minus the friction force, which is 20 N - 10 N = 10 N. The mass of the block is given as 10 kilograms. Therefore, the acceleration is 10 N / 10 kg = 1 m/s^2.