Answer: π/6.
- A π/6
- B 5π/6
- C π/3
- D 2π/3
Correct answer: A. π/6
Explanation: x(0) = A sin(φ) = A/2 → φ = π/6 or 5π/6. Velocity = Aω cos(φ). For positive velocity: cos(φ) > 0, so φ = π/6.
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.