Answer: 100 J.
- A 50 J
- B 100 J
- C 20 J
- D 200 J
Correct answer: B. 100 J
Explanation: KE = mgh = 2·10·5 = 100 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.