Question 1

A 80 N force is needed to slide a 50.0 kg box across a flat surface at a constant velocity.What is the coefficient of kinetic friction between the box and the floor? (Use g = 9.8 m/s2. )

Accepted Answer

A) 0.16 
B) 0.13 
C) 0.15 
D) 0.18

Question 2

A piano mover raises a 100 kg piano at a constant rate using a frictionless pulley system,as shown in the figure.With roughly what force is the mover pulling down on the rope?

Accepted Answer

A) 2000 N 
B) 1000 N 
C) 500 N 
D) 250 N 
E) Depends on the velocity!

Question 3

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 upper block,A?

Accepted Answer

A) 
 
B) 
 
C) 
 
D) 
 
E)

Question 4

The figure shows a 100 kg block being released from rest from a height of 1.0 m.It then takes 0.90 s to reach the floor.What is the mass of the block on the left?

Accepted Answer

A) 60 kg 
B) 54 kg 
C) 48 kg 
D) 42 kg

Question 5

Starting from rest,a 75 kg skier slides down a 17.0° slope.If the coefficient of kinetic friction between the skis and snow is 0.120 and it takes 16.9 s to get to the bottom,how long is the ski trail? (Use g = 9.8 m/s2. )

Accepted Answer

A) 248 m 
B) 496 m 
C) 124 m 
D) 186 m

Question 6

A 75 pound box rests on a perfectly smooth horizontal surface.Any horizontal force greater than zero will cause it to start moving.

Accepted Answer

A) True 
 B)False

Question 7

What is the mass of an object that experiences a gravitational force of 685 N near Earth's surface?

Accepted Answer

A) 69.9 kg 
B) 68.5 kg 
C) 71.3 kg 
D) 72.7 kg

Question 8

A device has a 100 g wooden shuttle that is pulled horizontally along a square frictionless wooden rail by an elastic band.The shuttle is released when the elastic band has 6.4 N tension at a 35º angle.What is the magnitude of the initial acceleration of the shuttle? (See the figure. )

Accepted Answer

A) 52 m/s2 
B) 37 m/s2 
C) 64 m/s2 
D) 62 m/s2

Question 9

An object at rest on an inclined plane starts to slide when the incline angle is increased to 17°.What is the coefficient of static friction between the object and the incline? (Use g = 9.8 m/s2. )

Accepted Answer

A) 0.31 
B) 0.27 
C) 0.33 
D) 0.37

Question 10

-Dick and Jane stand on a platform of negligible weight,as shown in the figure.Dick weighs 500 N and Jane weighs 400 N.Jane is supporting some of her weight on the end of the rope she is holding.What is the downward force she is exerting on the platform?

Accepted Answer

A) 0 
B) 50 N 
C) 100 N 
D) 240 N 
E) 300 N

Question 11

A skydiver reaches a "terminal velocity" of 120 km/h.If the skydiver has a mass of 59.0 kg,what is the magnitude of the upward force on the skydiver due to wind resistance? (Use g = 9.8 m/s2. )

Accepted Answer

A) 578 N 
B) 6.02 N 
C) 5.42 N 
D) 636 N

Question 12

If we step on the gas pedal of a car we will accelerate.Why don't we differentiate this action from braking? After all,when the brakes are applied the car decelerates,and that is different from accelerating.

Accepted Answer

The answer of If we step on the gas pedal...

Question 13

A person who normally weighs 200 pounds is standing on a scale inside an elevator.The elevator is moving upwards with a speed of 7 m/s,and then begins to slow down at a rate of 5 m/s2.Before the elevator begins to slow down,the reading of the scale is _________,and while the elevator is slowing down,the reading of the scale is ________.

Accepted Answer

A) 200 pounds,100 pounds 
B) greater than 200 pounds,100 pounds 
C) greater than 200 pounds,0 pounds 
D) less than 200 pounds,100 pounds 
E) None of the above

Question 14

A falling body accelerates downward until the drag force of the air is equal to the object's weight.After that point,the object will gradually come to rest.

Accepted Answer

A) True 
 B)False

Question 15

A cyclist is riding up a hill having a constant slope of 30º with respect to the horizon at a constant speed (in a straight line).Which statement is true?

Accepted Answer

A) The net force on the bike (due to gravity,the normal force,and friction)is zero. 
B) The net force on the bike (due to gravity,the normal force,and friction)is in the direction of motion. 
C) The net force on the bike (due to gravity,the normal force,and friction)is in the opposite direction of motion. 
D) None of the above statements are true.

Question 16

A 150 N box is being pulled horizontally in a wagon accelerating uniformly at 3.00 m/s2.The box does not move relative to the wagon,and the coefficient of static friction between the box and the wagon's surface is 0.600.The static friction force on this box is 90.0 N.

Accepted Answer

A) True 
 B)False

Question 17

Joe and Bill are playing tug-of-war.Joe is pulling with a force of 200 N.Bill is simply hanging on to the rope.Neither person is moving.What is the tension of the rope?

Accepted Answer

A) 200 N 
B) 400 N 
C) 0 N 
D) 300 N

Question 18

The figure shows a block of mass m resting on a 20° slope.The block has coefficients of friction µs = 0.55 and µk = 0.45 with the surface.It is connected via a massless string over a massless,frictionless pulley to a hanging block of mass 2.0 kg.What is the minimum mass m that will stick and not slip?

Accepted Answer

A) 2.3 kg 
B) 3.9 kg 
C) 1.4 kg 
D) 3.8 kg

Question 19

You are in a elevator which starts accelerating upward.Explain what happens to your apparent weight,and why.

Accepted Answer

The answer of You are in a elevator which starts...

Question 20

In a shuffleboard game,the puck slides a total of 12 m before coming to rest.If the coefficient of kinetic friction between the puck and board is 0.10,what was the initial speed of the puck?

Accepted Answer

A) 4.8 m/s 
B) 48.5 m/s 
C) 3.8 m/s 
D) 4.3 m/s

Exam 5: Applying Newtons Laws

A 80 N force is needed to slide a 50.0 kg box across a flat surface at a constant velocity.What is the coefficient of kinetic friction between the box and the floor? (Use g = 9.8 m/s². )

A piano mover raises a 100 kg piano at a constant rate using a frictionless pulley system,as shown in the figure.With roughly what force is the mover pulling down on the rope?

The figure shows a 100 kg block being released from rest from a height of 1.0 m.It then takes 0.90 s to reach the floor.What is the mass of the block on the left?

Starting from rest,a 75 kg skier slides down a 17.0° slope.If the coefficient of kinetic friction between the skis and snow is 0.120 and it takes 16.9 s to get to the bottom,how long is the ski trail? (Use g = 9.8 m/s². )

A 75 pound box rests on a perfectly smooth horizontal surface.Any horizontal force greater than zero will cause it to start moving.

What is the mass of an object that experiences a gravitational force of 685 N near Earth's surface?

A device has a 100 g wooden shuttle that is pulled horizontally along a square frictionless wooden rail by an elastic band.The shuttle is released when the elastic band has 6.4 N tension at a 35º angle.What is the magnitude of the initial acceleration of the shuttle? (See the figure. )

An object at rest on an inclined plane starts to slide when the incline angle is increased to 17°.What is the coefficient of static friction between the object and the incline? (Use g = 9.8 m/s². )

-Dick and Jane stand on a platform of negligible weight,as shown in the figure.Dick weighs 500 N and Jane weighs 400 N.Jane is supporting some of her weight on the end of the rope she is holding.What is the downward force she is exerting on the platform?

A skydiver reaches a "terminal velocity" of 120 km/h.If the skydiver has a mass of 59.0 kg,what is the magnitude of the upward force on the skydiver due to wind resistance? (Use g = 9.8 m/s². )

If we step on the gas pedal of a car we will accelerate.Why don't we differentiate this action from braking? After all,when the brakes are applied the car decelerates,and that is different from accelerating.

A falling body accelerates downward until the drag force of the air is equal to the object's weight.After that point,the object will gradually come to rest.

A cyclist is riding up a hill having a constant slope of 30º with respect to the horizon at a constant speed (in a straight line) .Which statement is true?

A 150 N box is being pulled horizontally in a wagon accelerating uniformly at 3.00 m/s2.The box does not move relative to the wagon,and the coefficient of static friction between the box and the wagon's surface is 0.600.The static friction force on this box is 90.0 N.

Joe and Bill are playing tug-of-war.Joe is pulling with a force of 200 N.Bill is simply hanging on to the rope.Neither person is moving.What is the tension of the rope?

You are in a elevator which starts accelerating upward.Explain what happens to your apparent weight,and why.

In a shuffleboard game,the puck slides a total of 12 m before coming to rest.If the coefficient of kinetic friction between the puck and board is 0.10,what was the initial speed of the puck?