Question 1

If a 5.0 kg box is pulled simultaneously by a 10.0 N force and a force,then its acceleration must be A) 3.0 m/s². B) 2.2 m/s². C) 1.0 m/s². D) We cannot tell from the information given.

Accepted Answer

D

Question 2

A fish weighing 16 N is weighed using two spring scales,each of negligible weight,as shown in the figure.What will be the readings of the scales? 
A) The bottom scale will read 16 N, and the top scale will read zero.
B) Each scale will read 16 N.
C) The top scale will read 16 N, and the bottom scale will read zero.
D) The scales will have different readings, but the sum of the two readings will be 16 N.
E) Each scale will read 8 N.

Accepted Answer

B

Question 3

An object is moving to the right,and experiencing a net force that is directed to the right.The magnitude of the force is decreasing with time.The speed of the object is
A) increasing.
B) decreasing.
C) constant in time.

Accepted Answer

Since the net force is directed to the right, the same direction as the object's motion, the object will accelerate in the direction of the force. Even if the magnitude of the force is decreasing, as long as it remains directed to the right and doesn't become zero or change direction, it will continue to cause the object's speed to increase, albeit at a decreasing rate.

Question 4

A block lies on a horizontal frictionless surface.A horizontal force of 100 N is applied to the block giving rise to an acceleration of  .
(a)Determine the mass of the block.
(b)Calculate the distance the block will travel if the force is applied for 10 s.
(c)Calculate the speed of the block after the force has been applied for 10 s.

Accepted Answer

The answer of A block lies on a horizontal frictionless...

Question 5

In order to get an object moving,you must push harder on it than it pushes back on you.

Accepted Answer

According to Newton's third law of motion, for every action, there is an equal and opposite reaction. This means that the force you apply to an object is exactly matched by the force the object applies back on you. The object moves not because you push harder, but because you apply a force that is unbalanced by other forces acting on the object, such as friction or gravity.

Question 6

Consider what happens when you jump up in the air.Which of the following is the most accurate statement? A) It is the upward force exerted by the ground that pushes you up, but this force cannot exceed your weight. B) You are able to spring up because the earth exerts a force upward on you that is greater than the downward force you exert on the earth. C) Since the ground is stationary, it cannot exert the upward force necessary to propel you into the air. Instead, it is the internal forces of your muscles acting on your body itself that propels your body into the air. D) When you push down on the earth with a force greater than your weight, the earth will push back with the same magnitude force and thus propel you into the air. E) When you jump up the earth exerts a force F₁ on you and you exert a force F₂ on the earth. You go up because .

Accepted Answer

The answer of Consider what happens when you jump up...

Question 7

Suppose you are playing hockey on a new-age ice surface for which there is no friction between the ice and the hockey puck.You wind up and hit the puck as hard as you can.After the puck loses contact with your stick,the puck will
A) start to slow down.
B) not slow down or speed up.
C) speed up a little, and then slow down.
D) speed up a little, and then move at a constant speed.

Accepted Answer

Since there is no friction, there are no forces acting on the puck to slow it down or speed it up. Therefore, the puck will continue to move at a constant speed in the direction it was hit until another force acts upon it.

Question 8

Two objects,each of weight W,hang vertically by spring scales as shown in the figure.The pulleys and the strings attached to the objects have negligible weight,and there is no appreciable friction in the pulleys.The reading in each scale is 
A) W.
B) more than W, but not quite twice as much.
C) less than W.
D) 2W.
E) more than 2W.

Accepted Answer

Since the two objects are in equilibrium, the tension in each string must be equal to the weight of the object it supports. Therefore, each scale reads W, and the total force in the system is 2W. None of the other choices are consistent with a system in equilibrium.

Question 9

You swing a bat and hit a heavy box with a force of 1500 N.The force the box exerts on the bat is
A) exactly 1500 N only if the box does not move.
B) exactly 1500 N whether or not the box moves.
C) greater than 1500 N if the box moves.
D) less than 1500 N if the box moves.
E) greater than 1500 N if the bat bounces back.

Accepted Answer

According to Newton's third law of motion, every action has an equal and opposite reaction. This means that the force with which the bat hits the box (1500 N) is also the force with which the box hits the bat. Therefore, the force the box exerts on the bat is exactly 1500 N, whether or not the box moves.

Question 10

A 20-ton truck collides with a 1500-lb car and causes a lot of damage to the car.During the collision
A) the force on the truck due to the collision is slightly greater than the force on the car.
B) the force of on the truck due to the collision is exactly equal to the force on the car.
C) the force on the car due to the collision is much greater than the force on the truck.
D) the car and the truck have the same magnitude acceleration.

Accepted Answer

According to Newton's third law of motion, for every action, there is an equal and opposite reaction. This means that the force exerted by the truck on the car is exactly equal in magnitude to the force exerted by the car on the truck during the collision.

Question 11

In order to lift a bucket of concrete,you must pull up harder on the bucket than it pulls down on you.

Accepted Answer

According to Newton's third law of motion, for every action, there is an equal and opposite reaction. Therefore, the force you exert to lift the bucket is equal in magnitude and opposite in direction to the gravitational force the bucket exerts downward.

Question 12

A ball is tossed vertically upward.When it reaches its highest point (before falling back downward)
A) the velocity is zero, the acceleration is directed downward, and the force of gravity acting on the ball is directed downward.
B) the velocity is zero, the acceleration is zero, and the force of gravity acting on the ball is zero.
C) the velocity is zero, the acceleration is zero, and the force of gravity acting on the ball is directed downward.
D) the velocity and acceleration reverse direction, but the force of gravity on the ball remains downward.
E) the velocity, acceleration, and the force of gravity on the ball all reverse direction.

Accepted Answer

At the highest point of its trajectory, a ball's velocity is zero because it stops for an instant before falling back down. However, acceleration due to gravity remains directed downward at approximately 9.8 m/s^2, and the force of gravity also continues to act downward on the ball. This is because gravity is a constant force acting on objects near Earth's surface, influencing their acceleration regardless of their momentary state of motion.

Question 13

A stalled car is being pushed up a hill at constant velocity by three people.The net force on the car is
A) zero.
B) up the hill and equal to the weight of the car.
C) down the hill and equal to the weight of the car.
D) up the hill and greater than the weight of the car.
E) down the hill and greater than the weight of the car.

Accepted Answer

Since the car is being pushed at a constant velocity, the net force on the car must be zero according to Newton's first law of motion. This means that the force applied by the three people pushing the car up the hill is equal and opposite to the force of friction and air resistance acting against the car. Thus, the net force on the car is zero.

Question 14

You are standing in a moving bus,facing forward,and you suddenly fall forward as the bus comes to an immediate stop.The force acting on you that causes you to fall forward is
A) the force of gravity.
B) the normal force due to your contact with the floor of the bus.
C) the force due to static friction between you and the floor of the bus.
D) the force due to kinetic friction between you and the floor of the bus.
E) No forces were acting on you to cause you to fall.

Accepted Answer

When the bus comes to an immediate stop, your body tends to continue moving forward due to inertia, not because of any external force acting on you in the forward direction. This is an example of Newton's first law of motion, which states that an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced external force. In this scenario, no external forward force is acting on you; you fall forward because the bus stops moving and your body tries to maintain its state of motion.

Question 15

You are seated in a bus and notice that a hand strap that is hanging from the ceiling hangs away from the vertical in the backward direction.From this observation,you can conclude that
A) the velocity of the bus is forward.
B) the velocity of the bus is backward.
C) You cannot conclude anything about the direction of the velocity of the bus.

Accepted Answer

The direction of the hand strap indicates acceleration, not velocity. The strap hanging backward suggests the bus is accelerating forward, but it doesn't provide information about the current velocity direction.

Question 16

Point P in the figure indicates the position of an object traveling at constant speed clockwise around the circle.Which arrow best represent the direction the object would travel if the net external force on it were suddenly reduced to zero? 
A) 
B) 
C) 
D) 
E)

Accepted Answer

The answer of Point P in the figure indicates the...

Question 17

A dog is standing in the bed of a pickup truck.The bed is coated with ice,causing the force of friction between the dog and the truck to be zero.The truck is initially at rest,and then accelerates to the right,moving along a flat road.As seen from a stationary observer (watching the truck move to the right),the dog
A) does not move left or right, but the back of the truck moves towards the dog.
B) moves to the right, but not as quickly as the truck is moving to the right, causing it to slide towards the back of the truck.
C) moves to the right at the same rate as the truck, so it doesn't slide.
D) moves to the left, as the truck moves to the right, causing the dog to slide towards the back of the truck.

Accepted Answer

Since there is no friction between the dog and the truck bed, the dog remains stationary relative to the ground as the truck accelerates to the right. This makes it appear as if the back of the truck moves towards the dog from the perspective of a stationary observer.

Question 18

An object is moving forward with a constant velocity.Which statement about this object MUST be true?
A) The net force on the object is zero.
B) The net force on the object is in the forward direction.
C) No forces are acting on the object.
D) The acceleration of the object is in the forward direction.

Accepted Answer

If an object is moving with constant velocity, it means that its speed and direction are not changing. Since acceleration is defined as a change in velocity (either in speed or direction), the object must have zero acceleration. According to Newton's second law, the net force on an object is equal to its mass times its acceleration. Therefore, if the object has zero acceleration, it must also have zero net force acting on it. Therefore, the correct statement is that the net force on the object is zero (choice A).

Question 19

A car is being towed at constant velocity on a horizontal road using a horizontal chain.The tension in the chain must be equal to the weight of the car in order to maintain constant velocity.

Accepted Answer

The tension in the chain must balance the frictional forces opposing the car's motion, not its weight, to maintain constant velocity. The weight of the car is counteracted by the normal force from the road.

Question 20

A box of mass m is pulled with a constant acceleration a along a horizontal frictionless floor by a wire that makes an angle of 15° above the horizontal.If T is the tension in this wire,then
A) T = ma.
B) T > ma.
C) T < ma.

Accepted Answer

Since the floor is frictionless, the only force acting on the box is the tension force T.

The weight of the box acts vertically down, and we can resolve it into two components - one along the horizontal direction (mg sin 15°) and the other along the vertical direction (mg cos 15°).

By Newton's second law, the horizontal component of the weight force is balanced by the tension force T. Thus, T = mg sin 15°.

The acceleration of the box in the horizontal direction is given by a = T/m, and substituting T = mg sin 15° gives a = g sin 15°.

Comparing with the given constant acceleration a, we can see that g sin 15° (which is greater than a) is the actual acceleration of the box.

Therefore, T = ma/g sin 15° > ma.

Quiz 4: Newtons Laws of Motion

If a 5.0 kg box is pulled simultaneously by a 10.0 N force and a force,then its acceleration must be

A fish weighing 16 N is weighed using two spring scales,each of negligible weight,as shown in the figure.What will be the readings of the scales?

An object is moving to the right,and experiencing a net force that is directed to the right.The magnitude of the force is decreasing with time.The speed of the object is

In order to get an object moving,you must push harder on it than it pushes back on you.

Consider what happens when you jump up in the air.Which of the following is the most accurate statement?

Suppose you are playing hockey on a new-age ice surface for which there is no friction between the ice and the hockey puck.You wind up and hit the puck as hard as you can.After the puck loses contact with your stick,the puck will

Two objects,each of weight W,hang vertically by spring scales as shown in the figure.The pulleys and the strings attached to the objects have negligible weight,and there is no appreciable friction in the pulleys.The reading in each scale is

You swing a bat and hit a heavy box with a force of 1500 N.The force the box exerts on the bat is

A 20-ton truck collides with a 1500-lb car and causes a lot of damage to the car.During the collision

In order to lift a bucket of concrete,you must pull up harder on the bucket than it pulls down on you.

A ball is tossed vertically upward.When it reaches its highest point (before falling back downward)

A stalled car is being pushed up a hill at constant velocity by three people.The net force on the car is

You are standing in a moving bus,facing forward,and you suddenly fall forward as the bus comes to an immediate stop.The force acting on you that causes you to fall forward is

You are seated in a bus and notice that a hand strap that is hanging from the ceiling hangs away from the vertical in the backward direction.From this observation,you can conclude that

Point P in the figure indicates the position of an object traveling at constant speed clockwise around the circle.Which arrow best represent the direction the object would travel if the net external force on it were suddenly reduced to zero?

An object is moving forward with a constant velocity.Which statement about this object MUST be true?

A car is being towed at constant velocity on a horizontal road using a horizontal chain.The tension in the chain must be equal to the weight of the car in order to maintain constant velocity.

A box of mass m is pulled with a constant acceleration a along a horizontal frictionless floor by a wire that makes an angle of 15° above the horizontal.If T is the tension in this wire,then