Question 1

A 615 N student standing on a scale in an elevator notices that the scale reads 645 N. From this information, the student knows that the elevator must be moving

Accepted Answer

A)  downward. 
B)  upward. 
C)  You cannot tell if it is moving upward or downward. 
A)  downward. 
B)  upward. 
C)  You cannot tell if it is moving upward or downward. C

Question 2

Which one of the following free-body diagrams best represents the free-body diagram, with correct relative force magnitudes, of a person in an elevator that is traveling upward but is gradually slowing down at a rate of 9 m/s2?   f is the force of the floor on the person and  
g is the force of gravity on the person.

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)    B

Question 3

On its own, a certain tow-truck has a maximum acceleration of 3.0 m/s2. What would be the maximum acceleration when this truck was towing a bus of twice its own mass?

Accepted Answer

A)  2.5 m/s2 
B)  2.0 m/s2 
C)  1.5 m/s2 
D)  1.0 m/s2 
A)  2.5 m/s2 
B)  2.0 m/s2 
C)  1.5 m/s2 
D)  1.0 m/s2 D

Question 4

The graph in the figure shows the x component of the acceleration of a 2.4-kg object as a function of time (in ms).   
(a) At what time(s) does the x component of the net force on the object reach its maximum magnitude, and what is that maximum magnitude?
(b) What is the x component of the net force on the object at time t = 0.0 ms and at t = 4.0 ms?

Accepted Answer

(a) At 3.0

Question 5

An 1100-kg car traveling at 27.0 m/s starts to slow down and comes to a complete stop in 578 m. What is the magnitude of the average braking force acting on the car?

Accepted Answer

A)  690 N 
B)  550 N 
C)  410 N 
D)  340 N 
A)  690 N 
B)  550 N 
C)  410 N 
D)  340 N

Question 6

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

A) True 
 B)False

Question 7

A woman is straining to lift a large crate, without success because it is too heavy. We denote the forces on the crate as follows: P is the upward force the woman exerts on the crate, C is the vertical contact force exerted on the crate by the floor, and W is the weight of the crate. How are the magnitudes of these forces related while the woman is trying unsuccessfully to lift the crate?

Accepted Answer

A)  P + C = W 
B)  P + C  W 
D)  P = C 
A)  P + C = W 
B)  P + C  W 
D)  P = C

Question 8

A crate is sliding down an inclined ramp at a constant speed of 0.55 m/s. The vector sum of all the forces acting on this crate must point down the ramp.

Accepted Answer

A) True 
 B)False

Question 9

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

Accepted Answer

A)  increasing. 
B)  decreasing. 
C)  constant in time. 
A)  increasing. 
B)  decreasing. 
C)  constant in time.

Question 10

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

Accepted Answer

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. 
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.

Question 11

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

Accepted Answer

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. 
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.

Question 12

The figure shows a graph of the acceleration of a 125-g object as a function of the net force acting on it. What is the acceleration at points A and B?

Accepted Answer

A: 16 m/s²,

Question 13

Which one of the following free-body diagrams best represents the free-body diagram, with correct relative force magnitudes, of a person in an elevator that is traveling upward with an unchanging velocity?   f is the force of the floor on the person and  
g is the force of gravity on the person.

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)

Question 14

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

Accepted Answer

A)  3.0 m/s2. 
B)  2.2 m/s2. 
C)  1.0 m/s2. 
D)  We cannot tell from the information given. 
A)  3.0 m/s2. 
B)  2.2 m/s2. 
C)  1.0 m/s2. 
D)  We cannot tell from the information given.

Question 15

The figure shows two forces, each of magnitude 4.6 N, acting on an object. The angle between these forces is 40°, and they make equal angles above and below the horizontal. What third force will cause the object to be in equilibrium (acceleration equals zero)?

Accepted Answer

A)  8.6 N pointing to the right 
B)  7.0 N pointing to the right 
C)  4.3 N pointing to the right 
D)  3.5 N pointing to the right 
A)  8.6 N pointing to the right 
B)  7.0 N pointing to the right 
C)  4.3 N pointing to the right 
D)  3.5 N pointing to the right

Question 16

A 7.0-kg object is acted on by two forces. One of the forces is 10.0 N acting toward the east. Which of the following forces is the other force if the acceleration of the object is 1.0 m/s2 toward the east?

Accepted Answer

A)  6.0 N east 
B)  3.0 N west 
C)  12 N east 
D)  9.0 N west 
E)  7.0 N west 
A)  6.0 N east 
B)  3.0 N west 
C)  12 N east 
D)  9.0 N west 
E)  7.0 N west

Question 17

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?

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)

Question 18

The graph in the figure shows the net force acting on a 3.0-kg object as a function of time.   
(a) What is the acceleration of this object at time t = 2.0 s?
(b) Draw, to scale, a graph of the acceleration of this object as a function of time over the range t = 0.00 s to t = 7.0 s.

Accepted Answer

(a) 2.0 m/s² (b) The accelerati

Question 19

The figure shows a graph of the acceleration of an object as a function of the net force acting on it. The mass of this object, in grams, is closest to

Accepted Answer

A)  130. 
B)  11. 
C)  89. 
D)  8000. 
A)  130. 
B)  11. 
C)  89. 
D)  8000.

Question 20

The figure shows two forces acting at right angles on an object. They have magnitudes   = 6.3 N and  
= 2.1 N. What third force will cause the object to be in equilibrium (acceleration equals zero)?

Accepted Answer

A)  6.6 N at 162° counterclockwise from   1 
B)  6.6 N at 108° counterclockwise from   1 
C)  4.2 N at 162° counterclockwise from   1 
D)  4.2 N at 108° counterclockwise from   1 
A)  6.6 N at 162° counterclockwise from   1 
B)  6.6 N at 108° counterclockwise from   1 
C)  4.2 N at 162° counterclockwise from   1 
D)  4.2 N at 108° counterclockwise from   1

Exam 5: Force and Motion

A 615 N student standing on a scale in an elevator notices that the scale reads 645 N. From this information, the student knows that the elevator must be moving

On its own, a certain tow-truck has a maximum acceleration of 3.0 m/s2. What would be the maximum acceleration when this truck was towing a bus of twice its own mass?

An 1100-kg car traveling at 27.0 m/s starts to slow down and comes to a complete stop in 578 m. What is the magnitude of the average braking force acting on the car?

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 crate is sliding down an inclined ramp at a constant speed of 0.55 m/s. The vector sum of all the forces acting on this crate must point down the ramp.

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

The figure shows a graph of the acceleration of a 125-g object as a function of the net force acting on it. What is the acceleration at points A and B?

Which one of the following free-body diagrams best represents the free-body diagram, with correct relative force magnitudes, of a person in an elevator that is traveling upward with an unchanging velocity? f is the force of the floor on the person and g is the force of gravity on the person.

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

The figure shows two forces, each of magnitude 4.6 N, acting on an object. The angle between these forces is 40°, and they make equal angles above and below the horizontal. What third force will cause the object to be in equilibrium (acceleration equals zero)?

A 7.0-kg object is acted on by two forces. One of the forces is 10.0 N acting toward the east. Which of the following forces is the other force if the acceleration of the object is 1.0 m/s2 toward the east?

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?

The graph in the figure shows the net force acting on a 3.0-kg object as a function of time. (a) What is the acceleration of this object at time t = 2.0 s? (b) Draw, to scale, a graph of the acceleration of this object as a function of time over the range t = 0.00 s to t = 7.0 s.

The figure shows a graph of the acceleration of an object as a function of the net force acting on it. The mass of this object, in grams, is closest to

The figure shows two forces acting at right angles on an object. They have magnitudes = 6.3 N and = 2.1 N. What third force will cause the object to be in equilibrium (acceleration equals zero)?

Concepts of Motion

Kinematics in One Dimension

Vectors and Coordinate Systems

Kinematics in Two Dimensions

Dynamics I: Motion Along a Line

Newtons Third Law

Dynamics Ii: Motion in a Plane

Impulse and Momentum

Energy

Work

Rotation of a Rigid Body

Newtons Theory of Gravity

Oscillations

Fluids and Elasticity

A Macroscopic Description of Matter

Work, Heat, and the First Law of Thermodynamics

The Micromacro Connection

Heat Engines and Refrigerators

Traveling Waves

Superpositions

Wave Optics

Ray Optics

Optical Instruments

Electric Charges and Forces

The Electric Field

Gausss Law

The Electric Potential

Potential and Field

Current and Resistance

Fundamentals of Circuits

The Magnetic Field

Electromagnetic Induction

Electromagnetic Fields and Waves

Ac Circuits

Relativity

The Foundations of Modern Physics

Quantization

Wave Functions and Uncertainty

One-Dimensional Quantum Mechanics

Atomic Physics

Nuclear Physics

Filters

On its own, a certain tow-truck has a maximum acceleration of 3.0 m/s². What would be the maximum acceleration when this truck was towing a bus of twice its own mass?

Which one of the following free-body diagrams best represents the free-body diagram, with correct relative force magnitudes, of a person in an elevator that is traveling upward with an unchanging velocity? _f is the force of the floor on the person and _g is the force of gravity on the person.

A 7.0-kg object is acted on by two forces. One of the forces is 10.0 N acting toward the east. Which of the following forces is the other force if the acceleration of the object is 1.0 m/s² toward the east?