Answer: 10 kW.
- A 5 kW
- B 10 kW
- C 20 kW
- D 100 kW
Correct answer: B. 10 kW
Explanation: Work = (1/2)(500)(20²) = 100000 J; average power = 100000/10 = 10 kW.
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.