Answer: Four times.
- A Double
- B Triple
- C Four times
- D Eight times
Correct answer: C. Four times
Explanation: KE = (1/2)mv2. If v doubles to 2v, KE = (1/2)m(2v)2 = 4 x (1/2)mv2. KE becomes 4 times.
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.