Question 1

A block of mass m sits at rest on a rough inclined ramp that makes an angle θ with the horizontal. What must be true about force of static friction f on the block?

Accepted Answer

A)  $f$ > mg 
B)  $f$ f > mg cos θ 
C)  $f$  > mg sin θ 
D)  $f$  = mg cos θ 
E)  $f$  = mg sin θ 
A)  $f$ > mg 
B)  $f$ f > mg cos θ 
C)  $f$  > mg sin θ 
D)  $f$  = mg cos θ 
E)  $f$  = mg sin θ

Question 2

Three boxes rest side-by-side on a smooth, horizontal floor. Their masses are 5.0 kg, 3.0 kg, and 2.0 kg, with the 3.0-kg mass in the center. A force of 50 N pushes on the 5.0-kg box, which pushes against the other two boxes. What magnitude force does the 5.0-kg box exert on the 3.0-kg box?

Accepted Answer

A)  0 N 
B)  10 N 
C)  25 N 
D)  40 N 
E)  50 N 
A)  0 N 
B)  10 N 
C)  25 N 
D)  40 N 
E)  50 N

Question 3

Jason takes off across level water on his jet-powered skis. The combined mass of Jason and his skis is 75 kg (the mass of the fuel is negligible). The skis produce a forward thrust of 200 N and have a coefficient of kinetic friction with water of 0.10. Unfortunately, the skis run out of fuel after only 90 s. What is Jason's top speed?

Accepted Answer

A)  150 m/s 
B)  240 m/s 
C)  24 m/s 
D)  90 m/s 
A)  150 m/s 
B)  240 m/s 
C)  24 m/s 
D)  90 m/s

Question 4

A 50-kg box is resting on a horizontal floor. A force of 250 N directed at an angle of 30.0° below the horizontal is applied to the box. The coefficient of static friction between the box and the surface is 0.40, and the coefficient of kinetic friction is 0.30. What is the force of friction on the box?

Accepted Answer

A)  32 N 
B)  200 N 
C)  220 N 
D)  250 N 
E)  620 N 
A)  32 N 
B)  200 N 
C)  220 N 
D)  250 N 
E)  620 N

Question 5

Two packages are connected by a very light string that goes over an ideal pulley as shown in the figure. Package A has a mass of 3.0 kg and can slide along a rough plane inclined at 30° above the horizontal. The string acts on package A parallel to the surface of the plane. The coefficient of static friction between package A and the plane is 0.40. What minimum mass should package B have in order to start package A sliding up the ramp?

Accepted Answer

The answer of Two packages are connected by a very...

Question 6

A 3.0-kg and a 5.0-kg box rest side-by-side on a perfectly smooth, level floor. A horizontal force of 32 N is applied to the 3.0-kg box pushing it against the 5.0-kg box, and, as a result, both boxes slide along the floor. How hard do the two boxes push against each other?

Accepted Answer

A)  12 N 
B)  20 N 
C)  24 N 
D)  32 N 
E)  0 N 
A)  12 N 
B)  20 N 
C)  24 N 
D)  32 N 
E)  0 N

Question 7

A push of magnitude P acts on a box of weight W as shown in the figure. The push is directed at an angle θ below the horizontal, and the box remains a rest. The box rests on a horizontal surface that has some friction with the box. The normal force on the box due to the floor is equal to

Accepted Answer

A)  W. 
B)  W + P. 
C)  W + P cos θ. 
D)  W + P sin θ. 
E)  W - P sin θ. 
A)  W. 
B)  W + P. 
C)  W + P cos θ. 
D)  W + P sin θ. 
E)  W - P sin θ.

Question 8

Two blocks, A and B, are being pulled to the right along a horizontal surface by a horizontal 100-N pull, as shown in the figure. Both of them are moving together at a constant velocity of 2.0 m/s to the right, and both weigh the same.   Which of the figures below shows a correct free-body diagram of the horizontal forces acting on the lower block, B?

Accepted Answer

A) 
  
B) 
  
C) 
  
D) 
  
E)  None of these diagrams is correct. 
A) 
  
B) 
  
C) 
  
D) 
  
E)  None of these diagrams is correct.

Question 9

Two boxes are connected to each other by a string as shown in the figure. The 10-N box slides without friction on the horizontal table surface. The pulley is ideal and the string has negligible mass. What is true about the tension T in the string?

Accepted Answer

A)  T = 10 N 
B)  T = 20 N 
C)  T = 30 N 
D)  T  30 N 
A)  T = 10 N 
B)  T = 20 N 
C)  T = 30 N 
D)  T  30 N

Question 10

An object is being acted upon by three forces and moves with a constant velocity. One force is 60 N along the +x-axis, the second is 75 N along a direction making a counterclockwise angle of 150° with the +x-axis.
(a) What is the magnitude of the third force?
(b) What is the direction of the third force, measured clockwise from the +x-axis?

Accepted Answer

The answer of An object is being acted upon by...

Question 11

A locomotive is pulling 9 freight cars, each of which is loaded with the same weight. The mass of each loaded car is $37,000 \mathrm {~kg}$ and we can neglect friction on these 9 cars. If the train is accelerating forward at $0.81 \mathrm {~m} / \mathrm { s } ^ { 2 }$ on a level track, what is the tension in the coupling between the second and third cars? (The car nearest the locomotive is counted as the first car.)

Accepted Answer

The answer of A locomotive is pulling 9 freight cars,...

Question 12

As shown in the figure, a 10-kg block on a perfectly smooth horizontal table is connected by a horizontal string to a 63-kg block that is hanging over the edge of the table. What is the magnitude of the acceleration of the 10-kg block when the other block is gently released?

Accepted Answer

A)  8.5 m/s2 
B)  8.1 m/s2 
C)  7.5 m/s2 
D)  9.0 m/s2 
A)  8.5 m/s2 
B)  8.1 m/s2 
C)  7.5 m/s2 
D)  9.0 m/s2

Question 13

A 15-kg block is on a frictionless ramp that is inclined at 20° above the horizontal. It is connected by a very light string over an ideal pulley at the top edge of the ramp to a hanging 19-kg block, as shown in the figure. The string pulls on the 15-kg block parallel to the surface of the ramp. Find the magnitude of the acceleration of the 19-kg block after the system is gently released?

Accepted Answer

A)  4.0 m/s2 
B)  3.8 m/s2 
C)  4.2 m/s2 
D)  4.5 m/s2 
A)  4.0 m/s2 
B)  3.8 m/s2 
C)  4.2 m/s2 
D)  4.5 m/s2

Question 14

A 3.0-kg mass and a 5.0-kg mass hang vertically at the opposite ends of a rope that goes over an ideal pulley. If the masses are gently released from rest, how long does it take for the 3.0-kg mass to rise by 1.0 m?

Accepted Answer

A)  0.41 s 
B)  0.74 s 
C)  0.82 s 
D)  1.8 s 
E)  0.90 s 
A)  0.41 s 
B)  0.74 s 
C)  0.82 s 
D)  1.8 s 
E)  0.90 s

Question 15

A 200-N sled of slides down a frictionless hillside that rises at 37° above the horizontal. What is the magnitude of the force that the hill exerts on the sled parallel to the surface of the hill?

Accepted Answer

A)  200 N 
B)  120 N 
C)  160 N 
D)  150 N 
E)  0 N 
A)  200 N 
B)  120 N 
C)  160 N 
D)  150 N 
E)  0 N

Question 16

You push horizontally on a 120-N box that is initially resting on a horizontal table. The coefficient of static friction between the box and the table is 0.75, and the coefficient of kinetic friction is 0.40. Find the friction force on the box if the push is equal to (a) 84 N; (b) 94 N.

Accepted Answer

The answer of You push horizontally on a 120-N box...

Question 17

You push downward on a trunk at an angle 25° below the horizontal with a force of $750 \mathrm {~N}$ If the trunk is on a flat surface and the coefficient of static friction between the surface and the trunk is 0.61, what is the most massive trunk you will be able to move?

Accepted Answer

A)  81 kg 
B)  93 kg 
C)  73 kg 
D)  112 kg 
A)  81 kg 
B)  93 kg 
C)  73 kg 
D)  112 kg

Question 18

A 1000-kg barge is being towed by means of two horizontal cables. One cable is pulling with a force of 80.0 N in a direction 30.0° west of north. In what direction should the second cable pull so that the barge will accelerate northward, if the force exerted by the cable is 120 N? Assume that the water exerts no appreciable frictional drag on the barge.

Accepted Answer

A)  19.5° east of north 
B)  21.1° east of north 
C)  39.0° east of north 
D)  47.5° east of north 
E)  54.7° east of north 
A)  19.5° east of north 
B)  21.1° east of north 
C)  39.0° east of north 
D)  47.5° east of north 
E)  54.7° east of north

Question 19

A 200-g hockey puck is launched up a ramp that is inclined at a 30° angle above the horizontal. The coefficients of static and kinetic friction between the puck and the ramp are µs = 0.40 and µk = 0.30, respectively, and the puck's initial velocity at the base is 3.8 m/s parallel to the sloping surface of the ramp. What speed does the puck have when it slides back down to its starting point?

Accepted Answer

Question 20

Two blocks, A and B, are being pulled to the right along a horizontal surface by a horizontal 100-N pull, as shown in the figure. Both of them are moving together at a constant velocity of 2.0 m/s to the right, and both weigh the same.   Which of the figures below shows a correct free-body diagram of the horizontal forces acting on the upper block, A?

Accepted Answer

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

A block of mass m sits at rest on a rough inclined ramp that makes an angle θ with the horizontal. What must be true about force of static friction f on the block?

Three boxes rest side-by-side on a smooth, horizontal floor. Their masses are 5.0 kg, 3.0 kg, and 2.0 kg, with the 3.0-kg mass in the center. A force of 50 N pushes on the 5.0-kg box, which pushes against the other two boxes. What magnitude force does the 5.0-kg box exert on the 3.0-kg box?

A 3.0-kg and a 5.0-kg box rest side-by-side on a perfectly smooth, level floor. A horizontal force of 32 N is applied to the 3.0-kg box pushing it against the 5.0-kg box, and, as a result, both boxes slide along the floor. How hard do the two boxes push against each other?

A push of magnitude P acts on a box of weight W as shown in the figure. The push is directed at an angle θ below the horizontal, and the box remains a rest. The box rests on a horizontal surface that has some friction with the box. The normal force on the box due to the floor is equal to

Two boxes are connected to each other by a string as shown in the figure. The 10-N box slides without friction on the horizontal table surface. The pulley is ideal and the string has negligible mass. What is true about the tension T in the string?

As shown in the figure, a 10-kg block on a perfectly smooth horizontal table is connected by a horizontal string to a 63-kg block that is hanging over the edge of the table. What is the magnitude of the acceleration of the 10-kg block when the other block is gently released?

A 3.0-kg mass and a 5.0-kg mass hang vertically at the opposite ends of a rope that goes over an ideal pulley. If the masses are gently released from rest, how long does it take for the 3.0-kg mass to rise by 1.0 m?

A 200-N sled of slides down a frictionless hillside that rises at 37° above the horizontal. What is the magnitude of the force that the hill exerts on the sled parallel to the surface of the hill?

You push horizontally on a 120-N box that is initially resting on a horizontal table. The coefficient of static friction between the box and the table is 0.75, and the coefficient of kinetic friction is 0.40. Find the friction force on the box if the push is equal to (a) 84 N; (b) 94 N.

You push downward on a trunk at an angle 25° below the horizontal with a force of $750 \mathrm {~N}$ If the trunk is on a flat surface and the coefficient of static friction between the surface and the trunk is 0.61, what is the most massive trunk you will be able to move?

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Thermal Properties of Matter

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Oscillations

Traveling Waves and Sound

Superposition and Standing Waves

Wave Optics

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Exam 5: Applying Newtons Laws

A block of mass m sits at rest on a rough inclined ramp that makes an angle θ with the horizontal. What must be true about force of static friction f on the block?

Three boxes rest side-by-side on a smooth, horizontal floor. Their masses are 5.0 kg, 3.0 kg, and 2.0 kg, with the 3.0-kg mass in the center. A force of 50 N pushes on the 5.0-kg box, which pushes against the other two boxes. What magnitude force does the 5.0-kg box exert on the 3.0-kg box?

A 3.0-kg and a 5.0-kg box rest side-by-side on a perfectly smooth, level floor. A horizontal force of 32 N is applied to the 3.0-kg box pushing it against the 5.0-kg box, and, as a result, both boxes slide along the floor. How hard do the two boxes push against each other?

A push of magnitude P acts on a box of weight W as shown in the figure. The push is directed at an angle θ below the horizontal, and the box remains a rest. The box rests on a horizontal surface that has some friction with the box. The normal force on the box due to the floor is equal to

Two boxes are connected to each other by a string as shown in the figure. The 10-N box slides without friction on the horizontal table surface. The pulley is ideal and the string has negligible mass. What is true about the tension T in the string?

As shown in the figure, a 10-kg block on a perfectly smooth horizontal table is connected by a horizontal string to a 63-kg block that is hanging over the edge of the table. What is the magnitude of the acceleration of the 10-kg block when the other block is gently released?

A 3.0-kg mass and a 5.0-kg mass hang vertically at the opposite ends of a rope that goes over an ideal pulley. If the masses are gently released from rest, how long does it take for the 3.0-kg mass to rise by 1.0 m?

A 200-N sled of slides down a frictionless hillside that rises at 37° above the horizontal. What is the magnitude of the force that the hill exerts on the sled parallel to the surface of the hill?

You push horizontally on a 120-N box that is initially resting on a horizontal table. The coefficient of static friction between the box and the table is 0.75, and the coefficient of kinetic friction is 0.40. Find the friction force on the box if the push is equal to (a) 84 N; (b) 94 N.

You push downward on a trunk at an angle 25° below the horizontal with a force of 750 N750 \mathrm {~N}750 N If the trunk is on a flat surface and the coefficient of static friction between the surface and the trunk is 0.61, what is the most massive trunk you will be able to move?

Representing Motion

Motion in One Dimension

Vectors and Motion in Two Dimensions

Forces and Newtons Laws of Motion

Gravity

Rotational Motion

Equilibrium Ad Elasticity

Momentum

Energy and Work

Using Energy

Thermal Properties of Matter

Fluids

Oscillations

Traveling Waves and Sound

Superposition and Standing Waves

Wave Optics

Ray Optics

Optical Instruments

Electric Fields and Forces

Electric Potential

Current and Resistance

Circuits

Magnetic Fields and Forces

EM Induction and Em Waves

AC Electricity

Relativity

Quantum Physics

Atoms and Molecules

Nuclear Physics

Filters

You push downward on a trunk at an angle 25° below the horizontal with a force of $750 \mathrm {~N}$ If the trunk is on a flat surface and the coefficient of static friction between the surface and the trunk is 0.61, what is the most massive trunk you will be able to move?