Answer: A/ 2.
- A A/2
- B A√2
- C A/√2
- D 2A
Correct answer: C. A/√2
Explanation: At the mean position speed v = Aω. Momentum conservation for the sudden sticking gives new speed v' = v/2 with mass 2m. New ω' = √(k/2m) = ω/√2, so A' = v'/ω' = (Aω/2)·(√2/ω) = A/√2.
In SHM, displacement and velocity are 90° out of phase (v is maximum when x=0, and zero when x is extreme), while acceleration is always exactly opposite in sign to displacement, consistent with a = −ω²x.
Concept context
Simple harmonic motion, spring-mass, pendulum, energy in SHM, and resonance.