Answer: 100 J.
- A 10 J
- B 50 J
- C 100 J
- D 200 J
Correct answer: C. 100 J
Explanation: KE = mgh = 2 x 10 x 5 = 100 J (all PE converted to KE in free fall).
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.