A 2.0-kg block slides down a frictionless incline from point A to point B. A force (magnitude P = 3.0 N) acts on the block between A and B, as shown. Points A and B are 2.0 m apart. If the kinetic energy of the block at A is 10 J, what is the kinetic energy of the block at B?
A)27 J
B)20 J
C)24 J
D)17 J
E)37 J

Question

A 2.0-kg block slides down a frictionless incline from point A to point B. A force (magnitude P = 3.0 N) acts on the block between A and B, as shown. Points A and B are 2.0 m apart. If the kinetic energy of the block at A is 10 J, what is the kinetic energy of the block at B? 
A)27 J 
B)20 J 
C)24 J 
D)17 J 
E)37 J

Quizplus · Accepted Answer

Since the incline is frictionless, the work done by the force P is equal to the change in kinetic energy of the block. Using the work-energy theorem:

W = ΔK

P × d = Kf - Ki

(3.0 N)(2.0 m) = Kf - 10 J

Kf = 6.0 J + 10 J

Kf = 16 J

Therefore, the kinetic energy of the block at B is 16 J.

A 20-Kg Block Slides Down a Frictionless Incline from Point a a to Point