Answer: 0.4 m.
- A 0.4 m
- B 1 m
- C 4 m
- D 2.5 m
Correct answer: A. 0.4 m
Explanation: T = 2π√(L/g). For T = 2 s and g = 4 m/s²: 2 = 2π√(L/4) → 1/π = √(L/4) → L/4 = 1/π² ≈ 0.101 → L ≈ 0.405 m.
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.