Answer: 24 J.
- A 12 J
- B 16 J
- C 24 J
- D 48 J
Correct answer: C. 24 J
Explanation: W = integral of F dx from 0 to 4 = integral of 3x dx = 3x<sup>2</sup>/2 from 0 to 4 = 3(16)/2 = 24 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.