Answer: A0/9.
- A A0/6
- B A0/9
- C A0/3
- D A0/27
Correct answer: B. A0/9
Explanation: Amplitude decays as A = A0e-γt. At 10 s, e-10γ = 1/3. At 20 s, e-20γ = (1/3)2 = 1/9, so the amplitude is A0/9.
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.