Answer: 1.5 J.
- A 0.5 J
- B 1.5 J
- C 3.0 J
- D 2.0 J
Correct answer: B. 1.5 J
Explanation: W = ½k(x<sub>2</sub><sup>2</sup> - x<sub>1</sub><sup>2</sup>) = ½ × 100 × (0.04 - 0.01) = ½ × 100 × 0.03 = 1.5 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.