Answer: 200 W.
- A 100 W
- B 200 W
- C 54 W
- D 12.5 W
Correct answer: B. 200 W
Explanation: For a force along the velocity, P = Fv = 50 N × 4 m/s = 200 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.