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Question :
11) If you do work a skateboard loaded with friends : 1519807

11) If you do work on a skateboard loaded with friends in one-third the usual time, you expend

A) one third as much power.

B) the usual power.

C) three times the usual power.

D) need more information.

12) The power expended doing 100 J of work in 50 s is

A) 1/2 W.

B) 2 W.

C) 4 W.

D) 50 W.

E) 5,000 W.

13) The power required to exert 4-N force over 3 meters in 2 seconds is

A) 4 W.

B) 6 W.

C) 8 W.

D) 12 W.

E) none of the above

14) Both a 50-kg sack is lifted 2 meters from the ground and a 25-kg sack is lifted 4 meters in the same time. The power expended in raising the 50-kg sack is

A) twice as much as the 25-kg sack.

B) half as much as the 25-kg sack.

C) the same.

D) need more information

15) A toy elevator is raised from the ground floor to the second floor in 20 seconds. The power needed using 1000 J of work, is

A) 20 W.

B) 50 W.

C) 100 W.

D) 1000 W.

E) 20,000 W.

16) The center of a long uniform log is raised to shoulder level while the other end is on the ground. If instead, the *end *of the log is raised to shoulder level, the work required is

A) half.

B) the same.

C) twice.

17) An object has gravitational potential energy due to its

A) speed.

B) acceleration.

C) momentum.

D) location.

E) none of the above

18) Relative to an initial height, an object raised twice as high has a gravitational potential energy

A) half as much

B) twice as much.

C) four times as much.

D) need more information

19) A crate of grapes lifted 10 meters gains 200 J of potential energy. If the same crate is instead lifted 20 meters, its gain in potential energy is

A) half as much.

B) the same.

C) twice as much.

D) four times as much.

E) more than four times as much.

20) When a drawn bow of potential energy 40 J is fired, the arrow will *ideally* have a kinetic energy

A) less than 40 J.

B) more than 40 J.

C) of 40 J.