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

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  • 1/91 Questions

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

    • Constant
    • Zero
    • G
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Chapter 4: Newton
About This Quiz

This quiz explores Newton's Second Law of Motion, focusing on concepts like mass, force, and acceleration. It tests understanding of mass measurement, the relationship between mass and inertia, and the gravitational forces acting as weight. Essential for students mastering physics fundamentals.

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  • 2. 

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

    • May be less than zero

    • Is zero

    • May be more than zero

    Correct Answer
    A. Is zero
    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.

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  • 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

    Correct Answer
    A. 5 N
    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.

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  • 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

    Correct Answer
    A. 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.

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  • 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

    Correct Answer
    A. 500 N
    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.

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  • 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

    Correct Answer
    A. 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.

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  • 7. 

    A force is a vector quantity because it has both

    • Magnitude and direction

    • Mass and acceleration

    • Action and reaction counterparts

    Correct Answer
    A. Magnitude and direction
    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.

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  • 8. 

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

    • 1 N

    • 4.9 N

    • 9.8 N

    • 10.8 N

    • None of these

    Correct Answer
    A. 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.

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  • 9. 

    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

    Correct Answer
    A. 3.0
    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.

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  • 10. 

    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

    Correct Answer
    A. 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.

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  • 11. 

    A kilogram is a measure of an object's

    • Weight

    • Force

    • Mass

    • Size

    Correct Answer
    A. 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.

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  • 12. 

    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

    Correct Answer
    A. 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.

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  • 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

    Correct Answer
    A. 10 N
    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.

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  • 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

    Correct Answer
    A. Has zero 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.

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  • 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

    Correct Answer
    A. The object eventually slides 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.

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  • 16. 

    Which has the greater mass?

    • A king-size pillow

    • An automobile battery

    • ) neither – both have the same

    Correct Answer
    A. An automobile battery
    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.

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  • 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

    Correct Answer
    A. 220
    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.

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  • 18. 

    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

    Correct Answer
    A. 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.

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  • 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

    Correct Answer
    A. 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.

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  • 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

    Correct Answer
    A. 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.

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  • 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

    Correct Answer
    A. 2
    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.

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  • 22. 

    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

    Correct Answer
    A. 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.

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  • 23. 

    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

    Correct Answer
    A. Head first
    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.

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  • 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

    Correct Answer
    A. 6 N
    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.

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  • 25. 

    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

    Correct Answer
    A. 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.

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  • 26. 

    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

    Correct Answer
    A. 10 times as much force
    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.

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  • 27. 

    Your weight is

    • Equal to your mass

    • The gravitational attraction force between you and the Earth

    • A property of mechanical equilibrium

    • All of these

    Correct Answer
    A. 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.

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  • 28. 

    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

    Correct Answer
    A. 0.5
    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.

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  • 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

    Correct Answer
    A. The light woman
    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.

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  • 30. 

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

    • Meters

    • Kilograms

    • Newtons

    • Cubic centimeters

    Correct Answer
    A. Newtons
    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.

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  • 31. 

    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

    Correct Answer
    A. About 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.

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  • 32. 

    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

    Correct Answer
    A. The same
    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.

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  • 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

    Correct Answer
    A. 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.

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  • 34. 

    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

    Correct Answer
    A. Less than 5 s
    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.

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  • 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

    Correct Answer
    A. 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.

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  • 36. 

    Which has zero acceleration? An object

    • At rest

    • Moving at constant velocity

    • In mechanical equilibrium

    • All of these

    • None of these

    Correct Answer
    A. All of these
    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.

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  • 37. 

    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

    Correct Answer
    A. 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.

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  • 38. 

    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

    Correct Answer
    A. 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.

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  • 39. 

    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

    Correct Answer
    A. The mass of the car is independent of 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.

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  • 40. 

    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

    Correct Answer
    A. Twice as much
    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.

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  • 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

    Correct Answer
    A. Any of the above may be correct
    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.

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  • 42. 

    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

    Correct Answer
    A. 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.

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  • 43. 

    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

    Correct Answer
    A. Continues 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.

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  • 44. 

    The newton is a unit of

    • Force

    • Mass

    • Density

    • Inertia

    Correct Answer
    A. 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.

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  • 45. 

    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

    Correct Answer
    A. Get a larger parachute
    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.

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  • 46. 

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

    • Increases

    • Decreases

    • Remains unchanged regardless of air resistance

    Correct Answer
    A. Decreases
    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.

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  • 47. 

    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

    Correct Answer
    A. Less
    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.

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  • 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

    Correct Answer
    A. Zero
    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.

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  • 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

    Correct Answer
    A. 30 m/s
    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.

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  • Current Version
  • Mar 17, 2023
    Quiz Edited by
    ProProfs Editorial Team
  • Sep 12, 2012
    Quiz Created by
    Drtaylor

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