Answer: -14 N.
- A -16 N
- B -14 N
- C 14 N
- D 16 N
Correct answer: B. -14 N
Explanation: F = -dU/dx = -(6x + 2). At x=2: F = -(12+2) = -14 N.
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.