Question 1

A constant force is applied to an object that causes a certain displacement. If the angle between the force and the displacement is 135°, the work done by this force is

Accepted Answer

A)   positive.
B)   negative.
C)   0 J.
D)   Cannot be determined without knowing the magnitude of the displacement.
E)   Cannot be determined without knowing the magnitude of the applied force.

Question 2

FIGURE 7-6 
-An object is under the influence of a force as represented by the force vs. position graph as shown in Figure 7-6. What is the work done as it moves from 10 to 15 m?

Accepted Answer

A)   25 J
B)   50 J
C)   100 J
D)   80 J
E)   125 J

Question 3

Power is a vector quantity.

Accepted Answer

A) True 
 B)False  False

Question 4

If the work done to stretch a spring by 4.0 cm is 6.0 J, what is the spring constant?

Accepted Answer

A)   300 N/m
B)   3000 N/m
C)   3500 N/m
D)   7500 N/m
E)   6000 N/m

Question 5

A 4.00-kg mass is attached to a spring hanging vertically and hangs at rest in the equilibrium position. The spring constant of the spring is 1.00 N/cm. The mass is pulled downward 2.00 cm and released. What is the speed of the mass when it is 1.00 cm above the point from which it was released?

Accepted Answer

A)   0.0443 m/s
B)   0.0744 m/s
C)   0.0201 m/s
D)   0.0866 m/s
E)   The mass will not reach the height specified.

Question 6

A boy throws a ball to another boy who throws it back with half the original speed. What is the ratio of the final kinetic energy to the initial kinetic energy of the ball?

Accepted Answer

A)   0.25
B)   0.50
C)   2.00
D)   0.75
E)   1.0

Question 7

I left five 100. watt bulbs burning in my basement for two weeks. If electricity costs me 10.¢/kw-h, how much did the electricity cost (to the nearest dollar) to leave these bulbs on and how many Joules of electrical energy did they consume?

Accepted Answer

$17.and 6....

Question 8

Work done by a force on an object can be a positive or a negative quantity.

Accepted Answer

A) True 
 B)False

Question 9

4.0 J of work are performed in stretching a spring with a spring constant of 2500 N/m. How much is the spring stretched?

Accepted Answer

A)   3.2 cm
B)   3.2 m
C)   0.3 cm
D)   5.7 m
E)   5.7 cm

Question 10

Compared to yesterday, you did 3 times the work in one-third the time. To do so, your power output must have been

Accepted Answer

A)   the same as yesterday's power output.
B)   one-third of yesterday's power output.
C)   3 times yesterday's power output.
D)   9 times yesterday's power output.
E)   34 times yesterday's power output.

Question 11

A 1.0-kg object moving in a certain direction has a kinetic energy of 2.0 J. It hits a wall and comes back with half its original speed. What is the kinetic energy of this object at this point?

Accepted Answer

A)   2.0 J
B)   1.0 J
C)   0.50 J
D)   0.25 J
E)   4.0 J

Question 12

Two men, Joel and Jerry, push against a wall. Jerry stops after 10 min, while Joel is able to push for 5.0 min longer. Compare the work they do.

Accepted Answer

A)   Joel does 75% more work than Jerry.
B)   Joel does 50% more work than Jerry.
C)   Jerry does 50% more work than Joel.
D)   Joel does 25% more work than Jerry.
E)   Neither of them do any work.

Question 13

What is the horsepower needed to change the speed of a 1600-kg sport utility vehicle from 15.0 m/s to 40.0 m/s in 4.00 seconds?

Accepted Answer

A)   369 hp
B)   36.9 hp
C)   18.8 hp
D)   188 hp
E)   275 hp

Question 14

Daisy raises 10.Kg to a height of 2.5 meters in 2.0 seconds.
(a) How much work did she do?
(b) How much power was expended?
(c) If she raises it in 1.0 s rather than 2.0 s, how do the work and power change?

Accepted Answer

(a)0.25 kJ
(b)0.12 k...

Question 15

Work is a vector quantity.

Accepted Answer

A) True 
 B)False  False

Question 16

FIGURE 7-1 
-Which of the graphs in Figure 7-1 represents a spring which gets less stiff the more it is stretched?

Accepted Answer

A)   graph a
B)   graph b
C)   graph c
D)   graph d
E)   none of these

Question 17

FIGURE 7-5 
-An object is under the influence of a force as represented by the force vs. position graph in Figure 7-5. What is the work done as the object moves from 4 m to 6 m?

Accepted Answer

A)   20 J
B)   30 J
C)   0 J
D)   40 J
E)   70 J A

Question 18

An object of mass m moving in a certain direction has a kinetic energy of 4.0 J. It hits a wall and comes back with half its original kinetic energy. If the speed of the object on return is 2.0 m/s, what is the mass of the object?

Accepted Answer

A)   2.0 kg
B)   2.8 kg
C)   3.8 kg
D)   1.0 kg
E)   4.0 kg

Question 19

An object of mass 10.0 kg is initially at rest. A 100 N force causes it to move horizontally through a distance of 6.00 m. What is the change in the kinetic energy of this object?

Accepted Answer

A)   0 J
B)   200 J
C)   60.0 J
D)   600 J
E)   1000 J

Question 20

An object of 1.0 kg mass is pulled up an inclined plane by a constant force of 10 N that causes a displacement of 0.50 m. The angle of inclination with the horizontal is 30°. Neglect friction and use g = 10 m/s2. What is the work done by the net force on the object along the inclined plane?

Accepted Answer

A)   4.3 J
B)   4.3 kg m/s2
C)   0 J
D)   2.5 J

Exam 7: Work and Kinetic Energy

A constant force is applied to an object that causes a certain displacement. If the angle between the force and the displacement is 135°, the work done by this force is

Correct AnswerverifiedShow Answer

FIGURE 7-6 -An object is under the influence of a force as represented by the force vs. position graph as shown in Figure 7-6. What is the work done as it moves from 10 to 15 m?

Correct AnswerverifiedShow Answer

Power is a vector quantity.

Correct AnswerverifiedFalse

If the work done to stretch a spring by 4.0 cm is 6.0 J, what is the spring constant?

Correct AnswerverifiedShow Answer

A 4.00-kg mass is attached to a spring hanging vertically and hangs at rest in the equilibrium position. The spring constant of the spring is 1.00 N/cm. The mass is pulled downward 2.00 cm and released. What is the speed of the mass when it is 1.00 cm above the point from which it was released?

Correct AnswerverifiedShow Answer

A boy throws a ball to another boy who throws it back with half the original speed. What is the ratio of the final kinetic energy to the initial kinetic energy of the ball?

Correct AnswerverifiedShow Answer

I left five 100. watt bulbs burning in my basement for two weeks. If electricity costs me 10.¢/kw-h, how much did the electricity cost (to the nearest dollar) to leave these bulbs on and how many Joules of electrical energy did they consume?

Correct Answerverified$17.and 6....View AnswerShow Answer

Work done by a force on an object can be a positive or a negative quantity.

Correct AnswerverifiedShow Answer

4.0 J of work are performed in stretching a spring with a spring constant of 2500 N/m. How much is the spring stretched?

Correct AnswerverifiedShow Answer

Compared to yesterday, you did 3 times the work in one-third the time. To do so, your power output must have been

Correct AnswerverifiedShow Answer

A 1.0-kg object moving in a certain direction has a kinetic energy of 2.0 J. It hits a wall and comes back with half its original speed. What is the kinetic energy of this object at this point?

Correct AnswerverifiedShow Answer

Two men, Joel and Jerry, push against a wall. Jerry stops after 10 min, while Joel is able to push for 5.0 min longer. Compare the work they do.

Correct AnswerverifiedShow Answer

What is the horsepower needed to change the speed of a 1600-kg sport utility vehicle from 15.0 m/s to 40.0 m/s in 4.00 seconds?

Correct AnswerverifiedShow Answer

Daisy raises 10.Kg to a height of 2.5 meters in 2.0 seconds. (a) How much work did she do? (b) How much power was expended? (c) If she raises it in 1.0 s rather than 2.0 s, how do the work and power change?

Correct Answerverified(a)0.25 kJ(b)0.12 k...View AnswerShow Answer

Work is a vector quantity.

Correct AnswerverifiedFalse

FIGURE 7-1 -Which of the graphs in Figure 7-1 represents a spring which gets less stiff the more it is stretched?

Correct AnswerverifiedShow Answer

FIGURE 7-5 -An object is under the influence of a force as represented by the force vs. position graph in Figure 7-5. What is the work done as the object moves from 4 m to 6 m?

Correct AnswerverifiedA

An object of mass m moving in a certain direction has a kinetic energy of 4.0 J. It hits a wall and comes back with half its original kinetic energy. If the speed of the object on return is 2.0 m/s, what is the mass of the object?

Correct AnswerverifiedShow Answer

An object of mass 10.0 kg is initially at rest. A 100 N force causes it to move horizontally through a distance of 6.00 m. What is the change in the kinetic energy of this object?

Correct AnswerverifiedShow Answer

An object of 1.0 kg mass is pulled up an inclined plane by a constant force of 10 N that causes a displacement of 0.50 m. The angle of inclination with the horizontal is 30°. Neglect friction and use g = 10 m/s2. What is the work done by the net force on the object along the inclined plane?

Correct AnswerverifiedShow Answer

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$17.and 6....
View Answer

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(a)0.25 kJ
(b)0.12 k...
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False

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A

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An object of 1.0 kg mass is pulled up an inclined plane by a constant force of 10 N that causes a displacement of 0.50 m. The angle of inclination with the horizontal is 30°. Neglect friction and use g = 10 m/s². What is the work done by the net force on the object along the inclined plane?

Correct Answer
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