Question 1

A 2.0-kg book is at rest on the horizontal desk. The normal force exerted on the book by the desk is

Accepted Answer

A)  2.0 kg. 
B)  2.0 N. 
C)  20 N. 
D)  200 N. 
E)  20 kg. 
A)  2.0 kg. 
B)  2.0 N. 
C)  20 N. 
D)  200 N. 
E)  20 kg. C

Question 2

A professor likes to demonstrate centripetal force by swinging a bucket of water in the vertical direction. What is the minimum speed he must swing the bucket at the top of the circle if he is not to get drenched? Assume that his arm is 1 m long.)

Accepted Answer

A)  1.1 m/s 
B)  2.1 m/s 
C)  3.1 m/s 
D)  4.1 m/s 
E)  5.1 m/s 
A)  1.1 m/s 
B)  2.1 m/s 
C)  3.1 m/s 
D)  4.1 m/s 
E)  5.1 m/s C

Question 3

A mass m is placed on a rough incline at an angle $\theta$ to the horizon. A force F is applied up the incline so that the mass slides up the incline. Using the compass rose, the direction of the frictional force is along

Accepted Answer

A)  a. 
B)  b. 
C)  c. 
D)  d. 
E)  e. 
A)  a. 
B)  b. 
C)  c. 
D)  d. 
E)  e. D

Question 4

The SI units for the coefficient of friction are

Accepted Answer

A)  newtons per meter. 
B)  meters. 
C)  newtons. 
D)  newtons times meters. 
E)  None of these is correct; the coefficient of friction has no units. 
A)  newtons per meter. 
B)  meters. 
C)  newtons. 
D)  newtons times meters. 
E)  None of these is correct; the coefficient of friction has no units.

Question 5

The figure shows a top view of a ball on the end of a string traveling counterclockwise in a circular path. The speed of the ball is constant. If the string should break at the instant shown, the path that the ball would follow is

Accepted Answer

A)  1). 
B)  2). 
C)  3). 
D)  4). 
E)  impossible to tell from the given information. 
A)  1). 
B)  2). 
C)  3). 
D)  4). 
E)  impossible to tell from the given information.

Question 6

A proud new Jaguar owner drives her car into a circular section of the width radius 30 m. The coefficients of friction between the road and the tires are 0.70 static) and 0.40 kinetic). What is the maximum speed she could drive around the corner without skidding?

Accepted Answer

A)  21 m/s 
B)  14 m/s 
C)  9.8 m/s 
D)  6.9 m/s 
E)  25 m/s 
A)  21 m/s 
B)  14 m/s 
C)  9.8 m/s 
D)  6.9 m/s 
E)  25 m/s

Question 7

A 2-kg block sits on an incline where the top part of the incline has a coefficient of kinetic friction $\mu$ k) of 0.70. The bottom section of the plane has $\mu$ k = 0.95. The angle of inclination is 40 degrees. The block is released and travels 10 m along the initial part of the incline and then enters the lower section. Calculate how far the block travels along the second section before it is brought to a stop.

Accepted Answer

A)  2.7 m 
B)  21 m 
C)  23 m 
D)  13 m 
E)  260 m 
A)  2.7 m 
B)  21 m 
C)  23 m 
D)  13 m 
E)  260 m

Question 8

A worker pushes a heavy 100-kg) crate that is resting on a thick pile carpet. The coefficients of static and kinetic friction are 0.6 and 0.4, respectively. The worker pushes with a horizontal force of 600 N. Use g = 9.8 m/s2. The acceleration of the crate will be

Accepted Answer

A)  9.8 m/s2. 
B)  4.9 m/s2. 
C)  3.5 m/s2. 
D)  2.1 m/s2. 
E)  0 m/s2. 
A)  9.8 m/s2. 
B)  4.9 m/s2. 
C)  3.5 m/s2. 
D)  2.1 m/s2. 
E)  0 m/s2.

Question 9

A worker pulls horizontally on a rope that is attached to a 10-kg crate resting on a rough floor. The coefficients of static and kinetic friction are 0.5 and 0.3, respectively. The worker pulls with a force of 40 N. The frictional force exerted by the surface is

Accepted Answer

A)  30 N. 
B)  50 N. 
C)  10 N. 
D)  100 N. 
E)  40 N. 
A)  30 N. 
B)  50 N. 
C)  10 N. 
D)  100 N. 
E)  40 N.

Question 10

A block of mass M is sliding down a rough inclined surface that makes an angle $\theta$ with respect to the horizontal. If the coefficient of static friction is $\mu$ s and kinetic friction $\mu$ k, then the acceleration of the block down the incline is equal to:

Accepted Answer

A)  "g sin $\theta$ - $\mu$ s g cos $\theta$." 
B)  " g cos$\theta$ - $\mu$ k g cos $\theta$" 
C)  "$\mu$ s g cos $\theta$ -g sin $\theta$" 
D)  "g sin $\theta$ -$\mu$ k g cos $\theta$" 
E)  "g sin $\theta$-$\mu$ s g cos $\theta$ - $\mu$ k g cos $\theta$" 
A)  "g sin $\theta$ - $\mu$ s g cos $\theta$." 
B)  " g cos$\theta$ - $\mu$ k g cos $\theta$" 
C)  "$\mu$ s g cos $\theta$ -g sin $\theta$" 
D)  "g sin $\theta$ -$\mu$ k g cos $\theta$" 
E)  "g sin $\theta$-$\mu$ s g cos $\theta$ - $\mu$ k g cos $\theta$"

Question 11

A worker pushes a heavy 100-kg) crate that is resting on a thick pile carpet. The coefficients of static and kinetic friction are 0.6 and 0.4, respectively. The worker pushes with a horizontal force of 600 N. Use g = 9.8 m/s2. The frictional force exerted by the surface is

Accepted Answer

A)  980 N. 
B)  588 N. 
C)  490 N. 
D)  392 N. 
E)  98 N. 
A)  980 N. 
B)  588 N. 
C)  490 N. 
D)  392 N. 
E)  98 N.

Question 12

When a particle moves in a circle with constant speed, its acceleration is

Accepted Answer

A)  constantly increasing. 
B)  constant in direction. 
C)  zero. 
D)  constant in magnitude. 
E)  constant in magnitude and direction. 
A)  constantly increasing. 
B)  constant in direction. 
C)  zero. 
D)  constant in magnitude. 
E)  constant in magnitude and direction.

Question 13

The figure shows a top view of a ball on the end of a string traveling counterclockwise in a circular path. Assume that air resistance is negligible. The free-body diagram that best represents the acceleration of the ball is

Accepted Answer

A)  1). 
B)  2). 
C)  3). 
D)  4). 
E)  5). 
A)  1). 
B)  2). 
C)  3). 
D)  4). 
E)  5).

Question 14

A 2.0-kg book is on the floor of an elevator. If the elevator is moving upward at a constant speed of 5.0 m/s, the normal force acting on the book is

Accepted Answer

A)  0 N. 
B)  2.0 N. 
C)  5.0 N. 
D)  10 N. 
E)  20 N. 
A)  0 N. 
B)  2.0 N. 
C)  5.0 N. 
D)  10 N. 
E)  20 N.

Question 15

A 100-kg block is pushed up a 30 o  incline at constant velocity. If the coefficient of friction between the block and the incline is 0.1, what constant force parallel to the incline is required to move the block?

Accepted Answer

A)  0.49 kN 
B)  0.085 kN 
C)  0.22 kN 
D)  0.80 kN 
E)  0.58 kN 
A)  0.49 kN 
B)  0.085 kN 
C)  0.22 kN 
D)  0.80 kN 
E)  0.58 kN

Question 16

Which of the following statements is NOT true about friction?

Accepted Answer

A)  µk is less than µs. 
B)  µk is independent of the relative speed of the surfaces in the range of about 1 cm/s to several meters per second. 
C)  µk depends on the relative speed of the surfaces at speeds over several meters per second. 
D)  The coefficients of friction depend on the nature of the surfaces. 
E)  The force of static friction depends on the area of contact between the two surfaces. 
A)  µk is less than µs. 
B)  µk is independent of the relative speed of the surfaces in the range of about 1 cm/s to several meters per second. 
C)  µk depends on the relative speed of the surfaces at speeds over several meters per second. 
D)  The coefficients of friction depend on the nature of the surfaces. 
E)  The force of static friction depends on the area of contact between the two surfaces.

Question 17

A block of mass m is pulled in the direction shown in the figure across a rough surface with a constant acceleration   . The magnitude of the frictional force is

Accepted Answer

A)  µkmg. 
B)  T cos $\theta$ - ma. 
C)  µkT - mg). 
D)  µkT sin $\theta$ 
E)  µkmg + sin $\theta$). 
A)  µkmg. 
B)  T cos $\theta$ - ma. 
C)  µkT - mg). 
D)  µkT sin $\theta$ 
E)  µkmg + sin $\theta$).

Question 18

A block is placed on an inclined plane with an angle of inclination $\theta$ in degrees) with respect to horizontal. The coefficient of static friction between the block and the inclined plane is 0.7. For what maximum value of $\theta$ will the block remain stationary on the inclined surface?

Accepted Answer

A)  35o 
B)  82o 
C)  44o 
D)  30o 
E)  18o 
A)  35o 
B)  82o 
C)  44o 
D)  30o 
E)  18o

Question 19

A block of wood is pulled by a horizontal string across a rough surface at a constant velocity with a force of 20 N. The coefficient of kinetic friction between the surfaces is 0.3. The force of friction is

Accepted Answer

A)  impossible to determine without knowing the mass of the block. 
B)  impossible to determine without knowing the speed of the block. 
C)  0.3 N. 
D)  6 N. 
E)  20 N. 
A)  impossible to determine without knowing the mass of the block. 
B)  impossible to determine without knowing the speed of the block. 
C)  0.3 N. 
D)  6 N. 
E)  20 N.

Question 20

A block with a mass of 10 kg is at rest on a horizontal surface. The coefficient of static friction between the block and the surface is 0.30, and the coefficient of kinetic friction is 0.25. A force of 20 N acts on the block toward the left. The magnitude of the frictional force on the block is

Accepted Answer

A)  10 N. 
B)  20 N. 
C)  0.10 kN. 
D)  30 N. 
E)  3.0 N. 
A)  10 N. 
B)  20 N. 
C)  0.10 kN. 
D)  30 N. 
E)  3.0 N.

Exam 5: Forces and Motion II: Applications

A 2.0-kg book is at rest on the horizontal desk. The normal force exerted on the book by the desk is

A professor likes to demonstrate centripetal force by swinging a bucket of water in the vertical direction. What is the minimum speed he must swing the bucket at the top of the circle if he is not to get drenched? Assume that his arm is 1 m long.)

A mass m is placed on a rough incline at an angle θ\thetaθ to the horizon. A force F is applied up the incline so that the mass slides up the incline. Using the compass rose, the direction of the frictional force is along

The SI units for the coefficient of friction are

The figure shows a top view of a ball on the end of a string traveling counterclockwise in a circular path. The speed of the ball is constant. If the string should break at the instant shown, the path that the ball would follow is

A proud new Jaguar owner drives her car into a circular section of the width radius 30 m. The coefficients of friction between the road and the tires are 0.70 static) and 0.40 kinetic). What is the maximum speed she could drive around the corner without skidding?

A worker pushes a heavy 100-kg) crate that is resting on a thick pile carpet. The coefficients of static and kinetic friction are 0.6 and 0.4, respectively. The worker pushes with a horizontal force of 600 N. Use g = 9.8 m/s2. The acceleration of the crate will be

A worker pulls horizontally on a rope that is attached to a 10-kg crate resting on a rough floor. The coefficients of static and kinetic friction are 0.5 and 0.3, respectively. The worker pulls with a force of 40 N. The frictional force exerted by the surface is

A block of mass M is sliding down a rough inclined surface that makes an angle θ\thetaθ with respect to the horizontal. If the coefficient of static friction is μ\muμ s and kinetic friction μ\muμ k, then the acceleration of the block down the incline is equal to:

A worker pushes a heavy 100-kg) crate that is resting on a thick pile carpet. The coefficients of static and kinetic friction are 0.6 and 0.4, respectively. The worker pushes with a horizontal force of 600 N. Use g = 9.8 m/s2. The frictional force exerted by the surface is

When a particle moves in a circle with constant speed, its acceleration is

The figure shows a top view of a ball on the end of a string traveling counterclockwise in a circular path. Assume that air resistance is negligible. The free-body diagram that best represents the acceleration of the ball is

A 2.0-kg book is on the floor of an elevator. If the elevator is moving upward at a constant speed of 5.0 m/s, the normal force acting on the book is

A 100-kg block is pushed up a 30 o incline at constant velocity. If the coefficient of friction between the block and the incline is 0.1, what constant force parallel to the incline is required to move the block?

Which of the following statements is NOT true about friction?

A block of mass m is pulled in the direction shown in the figure across a rough surface with a constant acceleration . The magnitude of the frictional force is

A block is placed on an inclined plane with an angle of inclination θ\thetaθ in degrees) with respect to horizontal. The coefficient of static friction between the block and the inclined plane is 0.7. For what maximum value of θ\thetaθ will the block remain stationary on the inclined surface?

A block of wood is pulled by a horizontal string across a rough surface at a constant velocity with a force of 20 N. The coefficient of kinetic friction between the surfaces is 0.3. The force of friction is

A block with a mass of 10 kg is at rest on a horizontal surface. The coefficient of static friction between the block and the surface is 0.30, and the coefficient of kinetic friction is 0.25. A force of 20 N acts on the block toward the left. The magnitude of the frictional force on the block is

Introduction to Physics

Linear Motion

Motion in Two and Three Dimensions

Forces and Motion I: Newtons Laws

Work and Energy

Momentum, Collisions, and the Center of Mass

Rotational Motion

Elastic Properties of Matter: Stress and Strain

Gravitation

Fluids

Oscillations

Waves

Thermodynamics I

Thermodynamics II

Electrostatics I: Electric Charge, Forces, and Fields

Electrostatics II: Electric Potential Energy and Electric Potential

Electric Charges in Motion

Magnetism

Electromagnetic Induction

Alternating-Current Circuits

Electromagnetic Waves

Wave Properties of Light

Geometrical Optics

Relativity

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A worker pushes a heavy 100-kg) crate that is resting on a thick pile carpet. The coefficients of static and kinetic friction are 0.6 and 0.4, respectively. The worker pushes with a horizontal force of 600 N. Use g = 9.8 m/s². The acceleration of the crate will be

A block of mass M is sliding down a rough inclined surface that makes an angle $\theta$ with respect to the horizontal. If the coefficient of static friction is $\mu$ _s and kinetic friction $\mu$ _k, then the acceleration of the block down the incline is equal to:

A worker pushes a heavy 100-kg) crate that is resting on a thick pile carpet. The coefficients of static and kinetic friction are 0.6 and 0.4, respectively. The worker pushes with a horizontal force of 600 N. Use g = 9.8 m/s². The frictional force exerted by the surface is

A 100-kg block is pushed up a 30^o incline at constant velocity. If the coefficient of friction between the block and the incline is 0.1, what constant force parallel to the incline is required to move the block?

A block is placed on an inclined plane with an angle of inclination $\theta$ in degrees) with respect to horizontal. The coefficient of static friction between the block and the inclined plane is 0.7. For what maximum value of $\theta$ will the block remain stationary on the inclined surface?