Answer: sqrt(10) m/s.
- A sqrt(5) m/s
- B sqrt(10) m/s
- C sqrt(15) m/s
- D sqrt(20) m/s
Correct answer: B. sqrt(10) m/s
Explanation: Height dropped: h = L(1 - cos60) = 1 x (1-0.5) = 0.5 m. v = sqrt(2gh) = sqrt(2 x 10 x 0.5) = sqrt(10) m/s.
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.