1. A force F of strength 20 N acts on an object of mass 3 kg as it moves a distance of 4 m. If F is perpendicular to the 4 m displacement, the work it does is equal to

(A) 0J
(B) 60J
(C) 801
(D) 600 J
(E) 2400 J

2. Under the influence of a force, an object of mass 4 kg accelerates from 3 m/s to 6 m/s in 8 s. How much work was done on the object during this time?

(A) 27 J
(B) 54 J
(C) 72 J
(D) 96 J
(E) Cannot be determined from the information given

3. A box of mass m slides down a frictionless inclined plane of length L and vertical height h. What is the change in its gravitational potential energy?

(A) -mgL
(B) -mgh
(C) -mgL/h
(D) -mgh/L
(E) -mghL

4. An object of mass m is traveling at constant speed v in a circular path of radius r. How much work is done by the centripetal force during one-half of a revolution?

(A) pmv²
(B) 2pmv²
(C) 0
(D) pmv²r
(E) 2pmv²r

5. While a person lifts a book of mass 2 kg from the floor to a tabletop, 1.5 m above the floor, how much work does the gravitational force do on the book?

(A) - 30 J
(B) - 15 J
(C) 0J
(D) 15 J
(E) 30 J

6. A block of mass 3.5 kg slides down a frictionless inclined plane of length 6 m that makes an angle of 30° with the horizontal. If the block is released from rest at the top of the incline, what is its speed at the bottom?

(A) 4.9 m/s
(B) 5.2 m/s
(C) 6.4 m/s
(D) 7.7 m/s
(E) 9.1 m/s

7. A block of mass 3.5 kg slides down an inclined plane of length 6 rn that makes an angle of 60° with the horizontal. The coefficient of kinetic friction between the block and the incline is 0.3. If the block is released from rest at the top of the incline, what is its speed at the bottom?

(A) 4.9 m/s
(B) 5.2 m/s
(C) 6.4 m/s
(D) 7.7 m/s
(E) 9.2 m/s

8. As a rock of mass 4 kg drops from the edge of a 40-meter-high cliff, it experiences air resistance, whose average strength during the descent is 20 N. At what speed will the rock hit the ground?

(A) 8 m/s
(B) 10 m/s
(C) 12 m/s
(D) 16 m/s
(E) 20 m/s

9. An astronaut drops a rock from the top of a crater on the Moon. When the rock is halfway down to the bottom of the crater, its speed is what fraction of its final impact speed?

(A) 1/4 
(B) 1/4
(C) 1/2 
(D) 1/2
(E) 1/

10. A force of 200 N is required to keep an object sliding at a constant speed of 2 m/s across a rough floor. How much power is being expended to maintain this motion?

(A) 50W
(B) 100W
(C) 200 W
(D) 400 W
(E) Cannot be determined from the information given