Answer: 50 J.
- A 2 J
- B 15 J
- C 50 J
- D 100 J
Correct answer: C. 50 J
Explanation: W = F x d = 10 x 5 = 50 J.
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.