Question 1

Energy conservation with conservative forces: A box of mass m is pressed against (but is not attached to)  an ideal spring of force constant k and negligible mass, compressing the spring a distance x. After it is released, the box slides up a frictionless incline as shown in the figure and eventually stops. If we repeat this experiment with a box of mass 2m

Accepted Answer

A)   the lighter box will go twice as high up the incline as the heavier box.
B)   just as it moves free of the spring, the lighter box will be moving twice as fast as the heavier box.
C)   both boxes will have the same speed just as they move free of the spring.
D)   both boxes will reach the same maximum height on the incline.
E)   just as it moves free of the spring, the heavier box will have twice as much kinetic energy as the lighter box.F) D) and E)
G) A) and C)

Question 2

Energy conservation with conservative forces: In the figure, a very small toy race car of mass m is released from rest on the loop-the-loop track. If it is released at a height 2R above the floor, how high is it above the floor when it leaves the track, neglecting friction?

Accepted Answer

A)   1.67 R
B)   2.00 R
C)   1.50 R
D)   1.33 R
E)   1.25 RF) D) and E)
G) B) and C)

Question 3

Energy conservation with nonconservative forces: A ball drops some distance and loses 30 J of gravitational potential energy. Do NOT ignore air resistance. How much kinetic energy did the ball gain?

Accepted Answer

A)   more than 30 J
B)   exactly 30 J
C)   less than 30 JD) A) and C)
E) B) and C)

Question 4

Work-energy theorem: A constant horizontal pull acts on a sled on a horizontal frictionless ice pond. The sled starts from rest. When the pull acts over a distance x, the sled acquires a speed v and a kinetic energy K. If the same pull instead acts over twice this distance:

Accepted Answer

A)   The sled's speed will be 2v and its kinetic energy will be 2K.
B)   The sled's speed will be 2v and its kinetic energy will be K  .
C)   The sled's speed will be v  and its kinetic energy will be 2K.
D)   The sled's speed will be v  and its kinetic energy will be K .
E)   The sled's speed will be 4v and its kinetic energy will be 2K.F) C) and D)
G) B) and C)

Question 5

Energy conservation with conservative forces: A block slides down a frictionless inclined ramp. If the ramp angle is 17.0° and its length is  find the speed of the block as it reaches the bottom of the ramp, assuming it started sliding from rest at the top.

Accepted Answer

A)   13.1 m/s
B)   172 m/s
C)   9.26 m/s
D)   24.0 m/sE) C) and D)
F) A) and B)

Question 6

Work: Three forces: F1 = 20.0 N, F2 = 40.0 N, and F3 = 10.0 N act on an object with a mass of 2.00 kg which can move along a frictionless inclined plane as shown in the figure. The questions refer to the instant when the object has moved through a distance of 0.600 m along the surface of the inclined plane in the upward direction. Calculate the amount of work done by
(a) F1
(b) F2
(c) F3

Accepted Answer

(a) 12.0 J...

Question 7

Power: How long will it take a 7.08 hp motor to lift a 250 kg beam directly upward at constant velocity from the ground to a height of 45.0 m? Assume frictional forces are negligible. (1 hp = 746 W)

Accepted Answer

A)   20.9 s
B)   1.56 × 104 s
C)   2.18 × 104 s
D)   39.7 sE) None of the above
F) A) and B)

Question 8

Energy conservation with nonconservative forces: Which, if any, of the following statements concerning the work done by a conservative force is NOT true?

Accepted Answer

A)   It can always be expressed as the difference between the initial and final values of a potential energy function.
B)   It is independent of the path of the body and depends only on the starting and ending points.
C)   When the starting and ending points are the same, the total work is zero.
D)   All of the above statements are true.
E)   None of the above statements are true.F) All of the above
G) A) and B)

Question 9

Energy conservation with nonconservative forces: A 1.37-kg block is held in place against the spring by a 74-N horizontal external force (see the figure) . The external force is removed, and the block is projected with a velocity v1 = 1.2 m/s upon separation from the spring. The block descends a ramp and has a velocity 1 = 1.2 m/s upon separation from the spring. The block descends a ramp and has a velocity   at the bottom. The track is frictionless between points A and B. The block enters a rough section at B, extending to E. The coefficient of kinetic friction over this section is 0.24. The velocity of the block is   at C. The block moves on to D, where it stops. The initial compression of the spring is closest to   A)  2.7 cm. B)  1.4 cm. C)  0.96 cm. D)  5.3 cm. E)  3.6 cm." class="answers-bank-image d-inline" rel="preload" > at the bottom. The track is frictionless between points A and B. The block enters a rough section at B, extending to E. The coefficient of kinetic friction over this section is 0.24. The velocity of the block is 1 = 1.2 m/s upon separation from the spring. The block descends a ramp and has a velocity   at the bottom. The track is frictionless between points A and B. The block enters a rough section at B, extending to E. The coefficient of kinetic friction over this section is 0.24. The velocity of the block is   at C. The block moves on to D, where it stops. The initial compression of the spring is closest to   A)  2.7 cm. B)  1.4 cm. C)  0.96 cm. D)  5.3 cm. E)  3.6 cm." class="answers-bank-image d-inline" rel="preload" > at C. The block moves on to D, where it stops. The initial compression of the spring is closest to 1 = 1.2 m/s upon separation from the spring. The block descends a ramp and has a velocity   at the bottom. The track is frictionless between points A and B. The block enters a rough section at B, extending to E. The coefficient of kinetic friction over this section is 0.24. The velocity of the block is   at C. The block moves on to D, where it stops. The initial compression of the spring is closest to   A)  2.7 cm. B)  1.4 cm. C)  0.96 cm. D)  5.3 cm. E)  3.6 cm." class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   2.7 cm.
B)   1.4 cm.
C)   0.96 cm.
D)   5.3 cm.
E)   3.6 cm.F) B) and D)
G) C) and E)

Question 10

Force and potential energy: The potential energy for a certain mass moving in one dimension is given by U(x)  = (2.0 J/m3) x3 - (15 J/m2) x2 + (36 J/m) x - 23 J. Find the location(s)  where the force on the mass is zero.

Accepted Answer

A)   4.0 m, 5.0 m
B)   1.0 m
C)   2.0 m, 3.0 m
D)   3.0 m, 5.0 mE) All of the above
F) B) and C)

Question 11

Work-energy theorem: The force on a 3.00-kg object as a function of position is shown in the figure. If an object is moving at 2.50 m/s when it is located at x = 2.00 m, what will its speed be when it reaches x = 8.00 m? (Assume that the numbers on the graph are accurate to 3 significant figures.)

Accepted Answer

A)   3.25 m/s
B)   3.70 m/s
C)   4.10 m/s
D)   2.90 m/s
E)   4.50 m/sF) D) and E)
G) B) and D)

Question 12

Work-energy theorem: If a force always acts perpendicular to an object's direction of motion, that force cannot change the object's kinetic energy.

Accepted Answer

A) True 
 B)False

Question 13

Work-energy theorem: A 1000 kg car experiences a net force of 9500 N while decelerating from 30.0 m/s to 23.4 m/s. How far does it travel while slowing down?

Accepted Answer

A)   18.5 m
B)   17.4 m
C)   20.2 m
D)   21.9 mE) All of the above
F) A) and B)

Question 14

Work: A graph of the force on an object as a function of its position is shown in the figure. Determine the amount of work done by this force on the object during a displacement from x = -2.00 m to x = 2.00 m. (Assume an accuracy of 3 significant figures for the numbers on the graph.)

Accepted Answer

A)   -12.0 J
B)   -3.00 J
C)   -1.00 J
D)   12.0 J
E)   3.00 JF) B) and E)
G) A) and D)

Question 15

Work done by variable forces: It requires 49 J of work to stretch an ideal very light spring from a length of 1.4 m to a length of 2.9 m. What is the value of the spring constant of this spring?

Accepted Answer

A)   15 N/m
B)   44 N/m
C)   29 N/m
D)   22 N/mE) None of the above
F) B) and C)

Question 16

Hooke's law: Block A (0.40 kg)  and block B (0.30 kg)  are on a frictionless table (see figure) . Spring 1 connects block A to a frictionless peg at 0 and spring 2 connects block A and block B. When the blocks are in uniform circular motion about 0, the springs have lengths of 0.60 m and 0.40 m, as shown. The springs are ideal and massless, and the linear speed of block B is 2.0 m/s. If the spring constant of spring 1 is equal to 30 N/m, the unstretched length of spring 1 is closest to

Accepted Answer

A)   0.51 m.
B)   0.52 m.
C)   0.53 m.
D)   0.54 m.
E)   0.55 m.F) C) and D)
G) B) and D)

Question 17

Work: A crane lifts a 425 kg steel beam vertically a distance of 2? Neglect frictional forces. A)  5.8 × 105 J B)  3.4 × 105 J C)  4.0 × 105 J D)  4.9 × 105 J" class="answers-bank-image d-inline" rel="preload" > How much work does the crane do on the beam if the beam accelerates upward at 1.8 m/s2? Neglect frictional forces.

Accepted Answer

A)   5.8 × 105 J
B)   3.4 × 105 J
C)   4.0 × 105 J
D)   4.9 × 105 JE) A) and C)
F) None of the above

Question 18

Energy conservation with conservative forces: An object is attached to a hanging unstretched ideal and massless spring and slowly lowered to its equilibrium position, a distance of 6.4 cm below the starting point. If instead of having been lowered slowly the object was dropped from rest, how far then would it then stretch the spring at maximum elongation?

Accepted Answer

A)   13 cm
B)   9.1 cm
C)   6.4 cm
D)   18 cm
E)   26 cmF) A) and D)
G) A) and C)

Question 19

Energy conservation with conservative forces: A 2.0 kg mass is moving along the x-axis. The potential energy curve as a function of position is shown in the figure. The kinetic energy of the object at the origin is 12 J. The system is conservative, and there is no friction.  (a) What will be the kinetic energy at 2.0 m along the +x-axis?
(b) What will be the speed of the object at 6.0 m along the +x-axis?

Accepted Answer

(a) 24 J
...

Question 20

Hooke's law: Which of the graphs in the figure illustrates Hooke's Law?

Accepted Answer

A)   Graph a
B)   Graph b
C)   Graph c
D)   graph dE) All of the above
F) A) and B)

Exam 6: Work and Kinetic Energy

Correct Answer
verified

Force and potential energy: The potential energy for a certain mass moving in one dimension is given by U(x) = (2.0 J/m³) x³- (15 J/m²) x²+ (36 J/m) x - 23 J. Find the location(s) where the force on the mass is zero.

Correct Answer
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Hooke's law: Which of the graphs in the figure illustrates Hooke's Law?

Correct Answer
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Energy conservation with conservative forces: A block slides down a frictionless inclined ramp. If the ramp angle is 17.0° and its length is find the speed of the block as it reaches the bottom of the ramp, assuming it started sliding from rest at the top.

Correct Answer
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Work-energy theorem: If a force always acts perpendicular to an object's direction of motion, that force cannot change the object's kinetic energy.

Correct Answer
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Power: How long will it take a 7.08 hp motor to lift a 250 kg beam directly upward at constant velocity from the ground to a height of 45.0 m? Assume frictional forces are negligible. (1 hp = 746 W)

Correct Answer
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Energy conservation with conservative forces: In the figure, a very small toy race car of mass m is released from rest on the loop-the-loop track. If it is released at a height 2R above the floor, how high is it above the floor when it leaves the track, neglecting friction?

Correct Answer
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Energy conservation with nonconservative forces: A ball drops some distance and loses 30 J of gravitational potential energy. Do NOT ignore air resistance. How much kinetic energy did the ball gain?

Correct Answer
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Work-energy theorem: A constant horizontal pull acts on a sled on a horizontal frictionless ice pond. The sled starts from rest. When the pull acts over a distance x, the sled acquires a speed v and a kinetic energy K. If the same pull instead acts over twice this distance:

Correct Answer
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Energy conservation with nonconservative forces: Which, if any, of the following statements concerning the work done by a conservative force is NOT true?

Correct Answer
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Work: A crane lifts a 425 kg steel beam vertically a distance of How much work does the crane do on the beam if the beam accelerates upward at 1.8 m/s²? Neglect frictional forces.

Correct Answer
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Correct Answer
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Correct Answer
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(a) 12.0 J...
View Answer

Correct Answer
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(a) 24 J
...
View Answer

Work-energy theorem: The force on a 3.00-kg object as a function of position is shown in the figure. If an object is moving at 2.50 m/s when it is located at x = 2.00 m, what will its speed be when it reaches x = 8.00 m? (Assume that the numbers on the graph are accurate to 3 significant figures.)

Correct Answer
verified

Work done by variable forces: It requires 49 J of work to stretch an ideal very light spring from a length of 1.4 m to a length of 2.9 m. What is the value of the spring constant of this spring?

Correct Answer
verified

Work-energy theorem: A 1000 kg car experiences a net force of 9500 N while decelerating from 30.0 m/s to 23.4 m/s. How far does it travel while slowing down?

Correct Answer
verified

Work: A graph of the force on an object as a function of its position is shown in the figure. Determine the amount of work done by this force on the object during a displacement from x = -2.00 m to x = 2.00 m. (Assume an accuracy of 3 significant figures for the numbers on the graph.)

Correct Answer
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Correct Answer
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Correct Answer
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Exam 6: Work and Kinetic Energy

Correct AnswerverifiedShow Answer

Force and potential energy: The potential energy for a certain mass moving in one dimension is given by U(x) = (2.0 J/m3) x3 - (15 J/m2) x2 + (36 J/m) x - 23 J. Find the location(s) where the force on the mass is zero.

Correct AnswerverifiedShow Answer

Hooke's law: Which of the graphs in the figure illustrates Hooke's Law?

Correct AnswerverifiedShow Answer

Energy conservation with conservative forces: A block slides down a frictionless inclined ramp. If the ramp angle is 17.0° and its length is find the speed of the block as it reaches the bottom of the ramp, assuming it started sliding from rest at the top.

Correct AnswerverifiedShow Answer

Work-energy theorem: If a force always acts perpendicular to an object's direction of motion, that force cannot change the object's kinetic energy.

Correct AnswerverifiedShow Answer

Power: How long will it take a 7.08 hp motor to lift a 250 kg beam directly upward at constant velocity from the ground to a height of 45.0 m? Assume frictional forces are negligible. (1 hp = 746 W)

Correct AnswerverifiedShow Answer

Energy conservation with conservative forces: In the figure, a very small toy race car of mass m is released from rest on the loop-the-loop track. If it is released at a height 2R above the floor, how high is it above the floor when it leaves the track, neglecting friction?

Correct AnswerverifiedShow Answer

Energy conservation with nonconservative forces: A ball drops some distance and loses 30 J of gravitational potential energy. Do NOT ignore air resistance. How much kinetic energy did the ball gain?

Correct AnswerverifiedShow Answer

Work-energy theorem: A constant horizontal pull acts on a sled on a horizontal frictionless ice pond. The sled starts from rest. When the pull acts over a distance x, the sled acquires a speed v and a kinetic energy K. If the same pull instead acts over twice this distance:

Correct AnswerverifiedShow Answer

Energy conservation with nonconservative forces: Which, if any, of the following statements concerning the work done by a conservative force is NOT true?

Correct AnswerverifiedShow Answer

Work: A crane lifts a 425 kg steel beam vertically a distance of How much work does the crane do on the beam if the beam accelerates upward at 1.8 m/s2? Neglect frictional forces.

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct Answerverified(a) 12.0 J...View AnswerShow Answer

Correct Answerverified(a) 24 J ...View AnswerShow Answer

Work-energy theorem: The force on a 3.00-kg object as a function of position is shown in the figure. If an object is moving at 2.50 m/s when it is located at x = 2.00 m, what will its speed be when it reaches x = 8.00 m? (Assume that the numbers on the graph are accurate to 3 significant figures.)

Correct AnswerverifiedShow Answer

Work done by variable forces: It requires 49 J of work to stretch an ideal very light spring from a length of 1.4 m to a length of 2.9 m. What is the value of the spring constant of this spring?

Correct AnswerverifiedShow Answer

Work-energy theorem: A 1000 kg car experiences a net force of 9500 N while decelerating from 30.0 m/s to 23.4 m/s. How far does it travel while slowing down?

Correct AnswerverifiedShow Answer

Work: A graph of the force on an object as a function of its position is shown in the figure. Determine the amount of work done by this force on the object during a displacement from x = -2.00 m to x = 2.00 m. (Assume an accuracy of 3 significant figures for the numbers on the graph.)

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct Answer
verified

Force and potential energy: The potential energy for a certain mass moving in one dimension is given by U(x) = (2.0 J/m³) x³- (15 J/m²) x²+ (36 J/m) x - 23 J. Find the location(s) where the force on the mass is zero.

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Work: A crane lifts a 425 kg steel beam vertically a distance of How much work does the crane do on the beam if the beam accelerates upward at 1.8 m/s²? Neglect frictional forces.

Correct Answer
verified

Correct Answer
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Correct Answer
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(a) 12.0 J...
View Answer

Correct Answer
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(a) 24 J
...
View Answer

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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