# Introduction To Dynamics: Newton's Laws Of Motion! Trivia Questions Quiz

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Have you just started your introduction to dynamics? The trivia questions quiz below is on Newton’s law of motion. There are three laws of motion, and each tries to explain what affects motion and how to correct some of the problems one may face. By trying out this quiz, you get a chance to refresh your mind on what you know. Do give it a shot!

• 1.

### Which of Newton's laws best explains why motorists should buckle-up?

• A.

The first law

• B.

The second law

• C.

The third law

• D.

The law of gravitation

A. The first law
Explanation
The first law of Newton, also known as the law of inertia, states that an object at rest will stay at rest, and an object in motion will stay in motion with the same speed and in the same direction unless acted upon by an external force. This law explains why motorists should buckle up because when a car suddenly stops, the passengers inside will continue moving forward due to inertia. Without seat belts, they would keep moving and potentially be thrown out of the car or collide with the dashboard or windshield, causing serious injury or death. Seat belts provide the necessary external force to keep passengers restrained and safe.

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• 2.

### When you sit on a chair, the resultant force on you is

• A.

Zero.

• B.

Up.

• C.

Down.

• D.

A. Zero.
Explanation
When you sit on a chair, the resultant force on you is zero because the force of gravity pulling you downwards is balanced by the normal force exerted by the chair in the opposite direction. This equilibrium of forces results in a net force of zero, causing you to remain stationary on the chair.

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• 3.

### In the absence of an external force, a moving object will

• A.

Stop immediately.

• B.

Slow down and eventually come to a stop.

• C.

Go faster and faster.

• D.

Move with constant velocity.

D. Move with constant velocity.
Explanation
In the absence of an external force, a moving object will move with constant velocity. This is because of the principle of inertia, which states that an object will continue to move at the same speed and in the same direction unless acted upon by an external force. Without any force to change its motion, the object will maintain a constant velocity.

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• 4.

### When the rocket engines on the starship NO-PAIN-NO-GAIN are suddenly turned off, while traveling in empty space, the starship will

• A.

Stop immediately.

• B.

Slowly slow down, and then stop.

• C.

Go faster and faster.

• D.

Move with constant speed.

D. Move with constant speed.
Explanation
When the rocket engines on the starship NO-PAIN-NO-GAIN are turned off in empty space, there is no external force acting on the starship to change its velocity. According to Newton's first law of motion, an object will continue to move with constant velocity unless acted upon by an external force. Therefore, the starship will continue to move with constant speed after the engines are turned off.

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• 5.

### A rocket moves through empty space in a straight line with constant speed. It is far from the gravitational effect of any star or planet. Under these conditions, the force that must be applied to the rocket in order to sustain its motion is

• A.

Equal to its weight.

• B.

Equal to its mass.

• C.

Dependent on how fast it is moving.

• D.

Zero.

D. Zero.
Explanation
In this scenario, since the rocket is far from any gravitational effect and is moving with constant speed, there is no need for any force to sustain its motion. According to Newton's first law of motion, an object in motion will stay in motion with constant velocity unless acted upon by an external force. Therefore, the force required to sustain the rocket's motion is zero.

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• 6.

### You are standing in a moving bus, facing forward, and you suddenly fall forward. You can imply from this that the bus's

• A.

Velocity decreased.

• B.

Velocity increased.

• C.

Speed remained the same, but it's turning to the right.

• D.

Speed remained the same, but it's turning to the left.

A. Velocity decreased.
Explanation
When you fall forward in a moving bus, it implies that the bus's velocity decreased. This is because velocity is a vector quantity that includes both speed and direction. In this scenario, the change in motion indicates a decrease in velocity rather than an increase or a change in direction. The speed of the bus may remain the same, but the decrease in velocity suggests that it is slowing down.

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• 7.

### You are standing in a moving bus, facing forward, and you suddenly fall forward as the bus comes to an immediate stop. What force caused you to fall forward?

• A.

Gravity

• B.

Normal force due to your contact with the floor of the bus

• C.

Force due to friction between you and the floor of the bus

• D.

Explanation
When the bus comes to an immediate stop, your body tends to continue moving forward due to inertia. In the absence of any external force, there is no force leading to your fall.

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• 8.

### A constant net force acts on an object. Describe the motion of the object.

• A.

Constant acceleration

• B.

Constant speed

• C.

Constant velocity

• D.

Increasing acceleration

A. Constant acceleration
Explanation
If a constant net force acts on an object, the object will experience a constant acceleration. This means that its velocity will change at a constant rate over time. The object will continue to accelerate in the same direction as the force, either increasing or decreasing its speed depending on the direction of the force. The motion of the object will not be at a constant speed or constant velocity, as these terms imply no change in speed or direction.

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• 9.

### The acceleration of an object is inversely proportional to

• A.

The net force acting on it.

• B.

Its position.

• C.

Its velocity.

• D.

Its mass.

D. Its mass.
Explanation
When the question states that the acceleration of an object is inversely proportional to something, it means that as that something increases, the acceleration decreases, and vice versa. In this case, the "something" is the mass of the object. 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. This means that as the mass of an object increases, its acceleration decreases, and as the mass decreases, the acceleration increases. Therefore, the correct answer is that the acceleration of an object is inversely proportional to its mass.

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• 10.

### A net force F accelerates a mass m with an acceleration a. If the same net force is applied to mass 2m, then the acceleration will be

• A.

4a.

• B.

2a.

• C.

A/2.

• D.

A/4.

C. A/2.
Explanation
When the same net force is applied to a mass that is twice as large, the resulting acceleration will be half of the original acceleration. This is because the acceleration is inversely proportional to the mass. Therefore, if the mass is doubled, the acceleration will be halved. Hence, the correct answer is a/2.

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• 11.

### A net force F acts on a mass m and produces an acceleration a. What acceleration results if a net force 2F acts on mass 4m?

• A.

A/2

• B.

8a

• C.

4a

• D.

2a

D. 2a
Explanation
When a net force F acts on a mass m, it produces an acceleration a. According to Newton's second law of motion, the acceleration is directly proportional to the net force and inversely proportional to the mass. So, if the net force is doubled to 2F and the mass is quadrupled to 4m, the acceleration will remain the same. Therefore, the acceleration resulting from a net force 2F acting on mass 4m is 2a.

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• 12.

### If you blow up a balloon, and then release it, the balloon will fly away. This is an illustration of

• A.

Newton's first law.

• B.

Newton's second law.

• C.

Newton's third law.

• D.

Galileo's law of inertia.

C. Newton's third law.
Explanation
When you blow up a balloon, you are filling it with air, creating pressure inside. When you release the balloon, the air rushes out in one direction, causing the balloon to move in the opposite direction according to Newton's third law of motion, which states that for every action, there is an equal and opposite reaction. The air rushing out of the balloon is the action, and the balloon flying away is the reaction. This demonstrates the principle of Newton's third law.

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• 13.

### Two cars collide head-on. At every moment during the collision, the magnitude of the force the first car exerts on the second is exactly equal to the magnitude of the force the second car exerts on the first. This is an example of

• A.

Newton's first law.

• B.

Newton's second law.

• C.

Newton's third law.

• D.

Newton's law of gravitation.

C. Newton's third law.
Explanation
This scenario is an example of Newton's third law of motion, which states that for every action, there is an equal and opposite reaction. In this case, the force exerted by the first car on the second car is equal in magnitude to the force exerted by the second car on the first car. This law explains the interaction between two objects and how their forces are always equal and opposite to each other.

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• 14.

### If you exert a force F on an object, the force which the object exerts on you will

• A.

Depend on whether or not the object is moving.

• B.

Depend on whether or not you are moving.

• C.

Depend on the relative masses of you and the object.

• D.

Always be F.

D. Always be F.
Explanation
The correct answer is "always be F." This is because of Newton's third law of motion, which states that for every action, there is an equal and opposite reaction. When you exert a force F on an object, the object exerts an equal force F back on you. This means that the force the object exerts on you will always be equal to the force you exert on it, regardless of whether the object or you are moving, or the relative masses of you and the object.

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• 15.

### Action-reaction forces

• A.

Sometimes act on the same object.

• B.

Always act on the same object.

• C.

May be at right angles.

• D.

Always act on different objects.

D. Always act on different objects.
Explanation
Action-reaction forces always occur in pairs, where one force is exerted on one object and the other force is exerted on a different object. According to Newton's third law of motion, for every action, there is an equal and opposite reaction. Therefore, the statement "always act on different objects" accurately describes the nature of action-reaction forces.

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• 16.

### Action-reaction forces are

• A.

Equal in magnitude and point in the same direction.

• B.

Equal in magnitude but point in opposite directions.

• C.

Unequal in magnitude but point in the same direction.

• D.

Unequal in magnitude and point in opposite directions.

B. Equal in magnitude but point in opposite directions.
Explanation
Action-reaction forces refer to the pair of forces that occur when two objects interact with each other. According to Newton's third law of motion, these forces are equal in magnitude, meaning they have the same strength. However, they point in opposite directions, which means they act in opposite ways on the two objects involved. This can be seen in everyday situations, such as when a person pushes against a wall - the person exerts a force on the wall, and the wall exerts an equal and opposite force back on the person.

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• 17.

### A 20-ton truck collides with a 1500-lb car and causes a lot of damage to the car. Since a lot of damage is done on the car

• A.

The force on the truck is greater then the force on the car.

• B.

The force on the truck is equal to the force on the car.

• C.

The force on the truck is smaller than the force on the car.

• D.

The truck did not slow down during the collision.

B. The force on the truck is equal to the force on the car.
Explanation
According to Newton's third law of motion, for every action, there is an equal and opposite reaction. In this case, the force exerted by the truck on the car is equal in magnitude and opposite in direction to the force exerted by the car on the truck. Therefore, the force on the truck is equal to the force on the car.

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• 18.

### An object of mass m sits on a flat table. The Earth pulls on this object with force mg, which we will call the action force. What is the reaction force?

• A.

The table pushing up on the object with force mg.

• B.

The object pushing down on the table with force mg.

• C.

The table pushing down on the floor with force mg.

• D.

The object pulling upward on the Earth with force mg.

D. The object pulling upward on the Earth with force mg.
Explanation
The reaction force in this scenario is the table pushing up on the object with force mg. According to Newton's third law of motion, for every action, there is an equal and opposite reaction. In this case, the action force is the Earth pulling on the object with force mg, and the reaction force is the table pushing up on the object with the same force mg. The other options are not correct because they do not represent the reaction force in this scenario.

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• 19.

### A child's toy is suspended from the ceiling by means of a string. The Earth pulls downward on the toy with its weight force of 8.0 N. If this is the "action force," what is the "reaction force"?

• A.

The string pulling upward on the toy with an 8.0-N force.

• B.

The ceiling pulling upward on the string with an 8.0-N force.

• C.

The string pulling downward on the ceiling with an 8.0-N force.

• D.

The toy pulling upward on the Earth with an 8.0-N force.

D. The toy pulling upward on the Earth with an 8.0-N force.
Explanation
The toy pulling upward on the Earth with an 8.0-N force is the reaction force because it is the force exerted by the toy on the Earth in response to the Earth's weight force pulling downward on the toy. According to Newton's third law of motion, for every action, there is an equal and opposite reaction. Therefore, the toy exerts an upward force on the Earth with the same magnitude as the Earth's weight force on the toy.

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• 20.

### A golf club hits a golf ball with a force of 2400 N. The golf ball hits the club with a force

• A.

Slightly less than 2400 N.

• B.

Exactly 2400 N.

• C.

Slightly more than 2400 N.

• D.

Close to 0 N.

B. Exactly 2400 N.
Explanation
When a golf club hits a golf ball, the force exerted on the ball is equal to the force exerted by the ball on the club, according to Newton's third law of motion. Therefore, the force with which the golf ball hits the club is exactly 2400 N, which is the same as the force applied by the club.

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• 21.

### Your bat hits the ball pitched to you with a 1500-N instantaneous force. The ball hits the bat with an instantaneous force, whose magnitude is

• A.

Somewhat less than 1500 N.

• B.

Somewhat greater than 1500 N.

• C.

Exactly equal to 1500 N.

• D.

Essentially zero.

C. Exactly equal to 1500 N.
Explanation
When the bat hits the ball, according to Newton's third law of motion, the ball exerts an equal and opposite force on the bat. This means that the force with which the ball hits the bat is exactly equal to the force with which the bat hits the ball. Therefore, the instantaneous force with which the ball hits the bat is exactly equal to 1500 N.

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• 22.

### Mass and weight

• A.

Both measure the same thing.

• B.

Are exactly equal.

• C.

Are two different quantities.

• D.

Are both measured in kilograms.

C. Are two different quantities.
Explanation
Mass and weight are two different quantities. Mass refers to the amount of matter in an object and is measured in kilograms. Weight, on the other hand, is the force exerted on an object due to gravity and is measured in newtons. While mass remains constant regardless of the gravitational pull, weight can vary depending on the strength of gravity. Therefore, although mass and weight are related, they are not the same thing.

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• 23.

### The acceleration due to gravity is lower on the Moon than on Earth. Which of the following is true about the mass and weight of an astronaut on the Moon's surface, compared to Earth?

• A.

Mass is less, weight is same.

• B.

Mass is same, weight is less.

• C.

Both mass and weight are less.

• D.

Both mass and weight are the same.

B. Mass is same, weight is less.
Explanation
The mass of an object remains the same regardless of the gravitational field it is in. Therefore, the mass of an astronaut on the Moon's surface would be the same as on Earth. However, weight is determined by the gravitational force acting on an object, which is lower on the Moon compared to Earth. Therefore, the weight of an astronaut on the Moon's surface would be less than on Earth.

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• 24.

### An example of a force which acts at a distance is

• A.

Tension.

• B.

Weight.

• C.

Static friction.

• D.

Kinetic friction.

B. Weight.
Explanation
Weight is an example of a force that acts at a distance because it is the force exerted by gravity on an object. Gravity acts on an object from a distance, pulling it towards the center of the Earth. This force is proportional to the mass of the object and acts in the direction towards the center of the Earth. Therefore, weight is a force that acts at a distance.

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• 25.

### Who has a greater weight to mass ratio, a person weighing 400 N or a person weighing 600 N?

• A.

The person weighing 400 N

• B.

The person weighing 600 N

• C.

Neither; their ratios are the same.

• D.

The question can't be answered; not enough information is given.

C. Neither; their ratios are the same.
Explanation
The weight to mass ratio is the same for both individuals because weight is proportional to mass. The weight to mass ratio is given by the equation weight = mass x gravity, where gravity is a constant. Since the value of gravity is the same for both individuals, their weight to mass ratios will also be the same. Therefore, neither person has a greater weight to mass ratio.

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• 26.

### A stone is thrown straight up. At the top of its path, the net force acting on it is

• A.

Greater than its weight.

• B.

Greater than zero, but less than its weight.

• C.

Instantaneously equal to zero.

• D.

Equal to its weight.

D. Equal to its weight.
Explanation
When a stone is thrown straight up, at the top of its path, the net force acting on it is equal to its weight. This is because at the top of its path, the stone momentarily comes to a stop before it starts falling back down due to the force of gravity. At this point, the force of gravity pulling the stone downwards is equal in magnitude to the force exerted by the person throwing the stone upwards, resulting in a net force of zero. Since weight is the force of gravity acting on an object, the net force being equal to the weight means that the stone is in equilibrium at the top of its path.

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• 27.

### A 20-N weight and a 5.0-N weight are dropped simultaneously from the same height. Ignore air resistance. Compare their accelerations.

• A.

The 20 N weight accelerates faster because it is heavier.

• B.

The 20 N weight accelerates faster because it has more inertia.

• C.

The 5.0 N weight accelerates faster because it has a smaller mass.

• D.

They both accelerate at the same rate because they have the same weight to mass ratio.

D. They both accelerate at the same rate because they have the same weight to mass ratio.
Explanation
The correct answer is that they both accelerate at the same rate because they have the same weight to mass ratio. This is because weight is directly proportional to mass, so when comparing the accelerations of two objects, their masses cancel out and only the gravitational force (weight) affects their acceleration. Therefore, regardless of their individual weights, objects will fall at the same rate in the absence of air resistance.

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• 28.

### A brick and a feather fall to the earth at their respective terminal velocities. Which object experiences the greater force of air friction?

• A.

The feather

• B.

The brick

• C.

Neither, both experience the same amount of air friction.

• D.

It cannot be determined because there is not enough information given.

B. The brick
Explanation
The brick experiences a greater force of air friction compared to the feather. This is because the force of air friction depends on the surface area and shape of the object. The brick has a larger surface area and a denser shape compared to the feather, which causes more air particles to collide with it and create a greater force of air friction.

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• 29.

### An object of mass m is hanging by a string from the ceiling of an elevator. The elevator is moving up at constant speed. What is the tension in the string?

• A.

Less than mg

• B.

Exactly mg

• C.

Greater than mg

• D.

Cannot be determined without knowing the speed

B. Exactly mg
Explanation
When the elevator is moving up at a constant speed, the object inside the elevator experiences an apparent weight equal to its actual weight. This means that the tension in the string must be equal to the weight of the object, which is given by the mass of the object multiplied by the acceleration due to gravity (mg). Therefore, the tension in the string is exactly mg.

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• 30.

### An object of mass m is hanging by a string from the ceiling of an elevator. The elevator is moving upward, but slowing down. What is the tension in the string?

• A.

Less than mg

• B.

Exactly mg

• C.

Greater than mg

• D.

Zero

A. Less than mg
Explanation
When the elevator is moving upward but slowing down, the tension in the string will be less than mg. This is because the acceleration of the elevator is in the opposite direction of the gravitational force acting on the object. As a result, the net force on the object is reduced, leading to a decrease in tension in the string.

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• 31.

### The force that keeps you from sliding on an icy sidewalk is

• A.

Weight.

• B.

Kinetic friction.

• C.

Static friction.

• D.

Normal force.

C. Static friction.
Explanation
Static friction is the force that keeps an object from sliding when there is no relative motion between the object and the surface it is in contact with. In the context of the question, static friction is the force that prevents a person from sliding on an icy sidewalk. This is because static friction opposes the motion or tendency of motion between two surfaces in contact, in this case, the person's shoes and the icy sidewalk. Therefore, static friction is the correct answer.

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• 32.

### A horizontal force accelerates a box from rest across a horizontal surface (friction is present) at a constant rate. The experiment is repeated, and all conditions remain the same with the exception that the horizontal force is doubled. What happens to the box's acceleration?

• A.

It increases to more than double its original value.

• B.

It increases to exactly double its original value.

• C.

It increases to less than double its original value.

• D.

It increases somewhat.

B. It increases to exactly double its original value.
Explanation
When a horizontal force is applied to accelerate a box from rest across a horizontal surface with friction, the acceleration of the box is determined by Newton's second law, which states that the acceleration of an object is directly proportional to the net force acting on the object and inversely proportional to its mass (a=F/m).
If the force is doubled and all other conditions (including mass and friction) remain the same, the net force acting on the box also doubles. Since the acceleration is directly proportional to the net force, the acceleration of the box would also double.

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• 33.

### A packing crate slides down an inclined ramp at constant velocity. Thus we can deduce that

• A.

A frictional force is acting on it.

• B.

A net downward force is acting on it.

• C.

It may be accelerating.

• D.

It is not acted on by appreciable gravitational force.

A. A frictional force is acting on it.
Explanation
The fact that the packing crate is sliding down the inclined ramp at a constant velocity suggests that there must be a force opposing its motion. This force is most likely friction, as it is the force that acts between two surfaces in contact and opposes their relative motion. If there were no frictional force, the crate would accelerate down the ramp due to the net downward force of gravity. Therefore, the presence of a frictional force is necessary to counterbalance the net downward force and maintain a constant velocity.

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• 34.

### A block of mass M slides down a frictionless plane inclined at an angle θ with the horizontal. The normal reaction force exerted by the plane on the block is

• A.

Mg.

• B.

Mg sin Î¸.

• C.

Mg cos Î¸.

• D.

Zero, since the plane is frictionless.

C. Mg cos Î¸.
Explanation
When a block slides down a frictionless inclined plane, the only forces acting on it are its weight and the normal reaction force exerted by the plane. The weight of the block is given by Mg, where M is the mass of the block and g is the acceleration due to gravity. The normal reaction force acts perpendicular to the plane and counteracts the component of the weight that is perpendicular to the plane. This component is given by Mg cos Î¸, where Î¸ is the angle of inclination. Therefore, the correct answer is Mg cos Î¸.

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• 35.

### A block of mass M slides down a frictionless plane inclined at an angle θ with the horizontal. The normal reaction force exerted by the plane on the block is directed

• A.

Parallel to the plane in the same direction as the movement of the block.

• B.

Parallel to the plane in the opposite direction as the movement of the block.

• C.

Perpendicular to the plane.

• D.

Toward the center of the Earth.

C. Perpendicular to the plane.
Explanation
The normal reaction force exerted by the plane on the block is directed perpendicular to the plane. This is because the normal force is always perpendicular to the surface on which an object rests. In this case, the block is on an inclined plane, so the normal force will be directed perpendicular to the plane.

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• 36.

### A block of mass M slides down a frictionless plane inclined at an angle θ with the horizontal. The gravitational force is directed

• A.

Parallel to the plane in the same direction as the movement of the block.

• B.

Parallel to the plane in the opposite direction as the movement of the block.

• C.

Perpendicular to the plane.

• D.

Toward the center of the Earth.

D. Toward the center of the Earth.
Explanation
The gravitational force is always directed towards the center of the Earth. In this scenario, as the block slides down the inclined plane, the gravitational force is still acting downwards towards the center of the Earth. This force is responsible for the acceleration of the block down the incline.

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• 37.

### Two toy cars (16 kg and 2.0 kg) are released simultaneously on an inclined plane that makes an angle of 30° with the horizontal. Make a statement which best describes their acceleration after being released.

• A.

The 16-kg car accelerates 8 times faster than the 2.0-kg car.

• B.

The 2.0-kg car accelerates 8 times faster than the 16-kg car.

• C.

Both cars accelerate at the same rate.

• D.

None of the above

C. Both cars accelerate at the same rate.
Explanation
The statement "Both cars accelerate at the same rate" is the correct answer because the acceleration of an object on an inclined plane depends only on the angle of the incline and not on the mass of the object. Therefore, both cars will experience the same acceleration regardless of their masses.

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• 38.

### An object sits on a frictionless surface. A 16-N force is applied to the object, and it accelerates at 2.0 m/s^2. What is the mass of the object?

• A.

4.0 kg

• B.

8.0 kg

• C.

32 kg

• D.

78 N

B. 8.0 kg
Explanation
The mass of an object can be calculated using the formula F = ma, where F is the force applied, m is the mass of the object, and a is the acceleration. In this case, the force applied is 16 N and the acceleration is 2.0 m/s^2. Rearranging the formula, we get m = F/a. Substituting the given values, we find that the mass of the object is 8.0 kg.

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• 39.

### A sports car of mass 1000 kg can accelerate from rest to 27 m/s in 7.0 s. What is the average forward force on the car?

• A.

2.6 * 10^2 N

• B.

3.9 * 10^3 N

• C.

2.7 * 10^4 N

• D.

1.9 * 10^5 N

B. 3.9 * 10^3 N
Explanation
The average forward force on the car 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 calculated by dividing the change in velocity (27 m/s) by the time taken (7.0 s). Plugging in these values into the equation, we get force = 1000 kg * (27 m/s / 7.0 s) = 3.857 * 10^3 N, which is closest to the given answer of 3.9 * 10^3 N.

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• 40.

### Starting from rest, a 4.0-kg body reaches a speed of 8.0 m/s in 2.0 s. What is the net force acting on the body?

• A.

4.0 N

• B.

8.0 N

• C.

16 N

• D.

32 N

C. 16 N
Explanation
The net force acting on an object can be calculated using Newton's second law, which states that force equals mass multiplied by acceleration. In this case, the mass of the body is given as 4.0 kg and the time taken to reach the speed is given as 2.0 s. To find the acceleration, we can use the formula acceleration equals change in velocity divided by time taken. The change in velocity is 8.0 m/s (final velocity) minus 0 m/s (initial velocity), divided by 2.0 s, which gives an acceleration of 4.0 m/s^2. Finally, we can calculate the net force by multiplying the mass (4.0 kg) by the acceleration (4.0 m/s^2), which equals 16 N.

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• 41.

### An antitank weapon fires a 3.00-kg rocket which acquires a speed of 50.0 m/s after traveling 90.0 cm down a launching tube. Assuming the rocket was accelerated uniformly, what is the average force acted on it?

• A.

4.17 * 10^3 N

• B.

3.62 * 10^3 N

• C.

2.82 * 10^3 N

• D.

2.00 * 10^3 N

A. 4.17 * 10^3 N
Explanation
The average force acted on the rocket can be calculated using the equation F = m * a, where F is the force, m is the mass, and a is the acceleration. In this case, the mass of the rocket is 3.00 kg and the acceleration can be calculated using the equation a = (vf - vi) / t, where vf is the final velocity, vi is the initial velocity, and t is the time. Since the rocket was accelerated uniformly, the initial velocity is 0 m/s. The final velocity is 50.0 m/s and the time can be calculated using the equation t = d / vf, where d is the distance traveled. Substituting the values into the equations, we can calculate the average force to be 4.17 * 10^3 N.

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• 42.

### If you push a 4.0-kg mass with the same force that you push a 10-kg mass from rest,

• A.

The 10-kg mass accelerates 2.5 times faster than the 4.0-kg mass.

• B.

The 4.0-kg mass accelerates 2.5 times faster than the 10-kg mass.

• C.

Both masses accelerate at the same rate.

• D.

None of the above is true.

B. The 4.0-kg mass accelerates 2.5 times faster than the 10-kg mass.
Explanation
The acceleration of an object is directly proportional to the force applied to it and inversely proportional to its mass. In this case, if the same force is applied to both the 4.0-kg mass and the 10-kg mass, the 4.0-kg mass will experience a greater acceleration because it has a smaller mass. Since the acceleration is inversely proportional to the mass, the 4.0-kg mass will accelerate 2.5 times faster than the 10-kg mass.

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• 43.

### What is the mass of a person who weighs 110 lb?

• A.

50 kg

• B.

55 kg

• C.

110 kg

• D.

242 kg

A. 50 kg
Explanation
The mass of a person who weighs 110 lb is 50 kg. This is because 1 lb is approximately equal to 0.45 kg. Therefore, to convert the weight from lb to kg, we divide 110 by 2.2, which gives us 50 kg.

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• 44.

### What is the mass of an object that weighs 250 N on the surface of the Earth where the acceleration due to gravity is 9.80 m/s^2?

• A.

250 kg

• B.

24.5 kg

• C.

25.5 kg

• D.

2,450 kg

C. 25.5 kg
Explanation
The mass of an object can be calculated using the formula: mass = weight / acceleration due to gravity. In this case, the weight of the object is given as 250 N and the acceleration due to gravity is 9.80 m/s^2. By substituting these values into the formula, we can find that the mass of the object is 25.5 kg.

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• 45.

### An object has a mass of 60 kg on the Earth. What is the mass of the object on the surface of the Moon where the acceleration due to gravity is only 1/6 of that on the Earth?

• A.

6.0 kg

• B.

10 kg

• C.

60 kg

• D.

360 kg

C. 60 kg
Explanation
The mass of an object remains the same regardless of the location or gravitational force acting on it. Therefore, the mass of the object on the surface of the Moon is still 60 kg.

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• 46.

### Object A weighs 40 N on Earth, and object B weighs 40 N on the Moon. The Moon's gravity is one sixth of Earth's. Compare the masses of the objects.

• A.

A has 6 times the mass of B.

• B.

B has 6 times the mass of A.

• C.

A and B have equal mass.

• D.

The situation as stated is impossible.

B. B has 6 times the mass of A.
Explanation
Since weight is directly proportional to mass and the weight of object B on the Moon is the same as the weight of object A on Earth, we can conclude that the masses of the two objects are different. Since the Moon's gravity is one sixth of Earth's, object B must have a greater mass than object A in order to have the same weight. Therefore, B has 6 times the mass of A.

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• 47.

### Sue and Sean are having a tug-of-war by pulling on opposite ends of a 5.0-kg rope. Sue pulls with a 15-N force. What is Sean's force if the rope accelerates toward Sue at 2.0 m/s^2?

• A.

3.0 N

• B.

5.0 N

• C.

25 N

• D.

50 N

B. 5.0 N
Explanation
Sue is pulling on the rope with a force of 15 N. The rope has a mass of 5.0 kg and is accelerating towards Sue at 2.0 m/s^2. According to Newton's second law of motion, force is equal to mass multiplied by acceleration (F = ma). Therefore, the total force acting on the rope is equal to the product of its mass and acceleration, which is (5.0 kg)(2.0 m/s^2) = 10 N. Since Sue is pulling on the rope with a force of 15 N, Sean's force must be equal to the total force minus Sue's force, which is 10 N - 15 N = -5 N. However, force cannot be negative, so Sean's force is 0 N. Therefore, the correct answer is 5.0 N.

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• 48.

### A stack of books rests on a level frictionless surface. A force F acts on the stack, and it accelerates at 3.0 m/s^2. A 1.0 kg book is then added to the stack. The same force is applied, and now the stack accelerates at 2.0 m/s^2. What was the mass of the original stack?

• A.

1.0 kg

• B.

2.0 kg

• C.

3.0 kg

• D.

None of the above

B. 2.0 kg
Explanation
When the force F is applied to the original stack, it accelerates at 3.0 m/s^2. This means that the net force acting on the stack is equal to the mass of the stack multiplied by the acceleration. Let's denote the mass of the original stack as M.

So, the net force on the original stack is F = M * 3.0 m/s^2.

When the 1.0 kg book is added to the stack, the same force F is applied, but now the stack accelerates at 2.0 m/s^2. This means that the net force acting on the stack is equal to the mass of the stack plus the mass of the added book, multiplied by the acceleration.

So, the net force on the stack with the added book is F = (M + 1.0 kg) * 2.0 m/s^2.

Since the force F is the same in both cases, we can equate the two expressions for the net force:

M * 3.0 m/s^2 = (M + 1.0 kg) * 2.0 m/s^2.

Simplifying this equation, we get:

3M = 2M + 2.0 kg.

M = 2.0 kg.

Therefore, the mass of the original stack was 2.0 kg.

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• 49.

### A person of weight 480 N stands on a scale in an elevator. What will the scale be reading when the elevator is accelerating downward at 4.00 m/s^2?

• A.

196 N

• B.

284 N

• C.

676 N

• D.

480 N

B. 284 N
Explanation
When the elevator is accelerating downward at 4.00 m/s^2, there will be an additional downward force acting on the person due to the acceleration. This force is equal to the mass of the person multiplied by the acceleration. Since weight is equal to mass multiplied by gravity, the person's weight will increase by this additional force. Therefore, the scale will be reading a higher value than the person's actual weight. The correct answer of 284 N represents the person's weight plus the additional force due to acceleration.

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• 50.

### A person on a scale rides in an elevator. If the mass of the person is 60.0 kg and the elevator accelerates downward with an acceleration of 4.90 m/s^2, what is the reading on the scale?

• A.

147 N

• B.

294 N

• C.

588 N

• D.

882 N

B. 294 N
Explanation
When a person is standing on a scale, the scale measures the normal force exerted by the person on the scale. In this case, the person's weight is equal to their mass multiplied by the acceleration due to gravity (9.8 m/s^2). However, since the elevator is accelerating downward, there is an additional force acting on the person, causing the scale reading to be less than their actual weight. The net force acting on the person can be calculated using Newton's second law (F = ma), where the mass is 60.0 kg and the acceleration is -4.90 m/s^2 (negative because it is downward). The net force is then equal to the person's weight minus the force due to the acceleration of the elevator. Therefore, the reading on the scale is equal to the net force, which is 294 N.

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• Apr 05, 2024
Quiz Edited by
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• Sep 13, 2012
Quiz Created by
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