Answer: 500 W.
- A 500 W
- B 1000 W
- C 3000 W
- D 6000 W
Correct answer: A. 500 W
Explanation: P = mgh/t = 60 x 10 x 50 / 60 = 500 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.