Answer: H/4.
- A H/2
- B H/3
- C H/4
- D 3H/4
Correct answer: C. H/4
Explanation: At height h: PE = mgh, KE = mg(H - h). Setting KE = 3PE gives H - h = 3h, so H = 4h and h = H/4.
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.