Answer: sqrt(h/H).
- A sqrt(h/H)
- B h/H
- C sqrt(H/h)
- D H/h
Correct answer: A. sqrt(h/H)
Explanation: e = speed after / speed before = sqrt(2gh) / sqrt(2gH) = sqrt(h/H).
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.