Answer: 150 W.
- A 9 W
- B 15 W
- C 150 W
- D 9000 W
Correct answer: C. 150 W
Explanation: W = mgh = 60 x 10 x 15 = 9000 J. P = W/t = 9000/60 = 150 W.
As a pendulum swings, total mechanical energy (KE+PE) stays constant: at the highest points A and C, all energy is potential (zero speed); at the lowest point B, all of that energy has converted into kinetic energy (maximum speed).
Concept context
Work-energy theorem, potential energy, conservation of energy, collisions.