Answer: 16 J.
- A 32 J
- B 8 J
- C 16 J
- D 4 J
Correct answer: C. 16 J
Explanation: By the work-energy theorem, W = ½m(v<sup>2</sup> - u<sup>2</sup>) = ½ × 2 × (25 - 9) = 16 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.