Answer: x = A/√2.
- A x = A/√2
- B x = A/2
- C x = A
- D x = 0
Correct answer: A. x = A/√2
Explanation: KE = PE when (1/2)k(A²-x²) = (1/2)kx² → A² = 2x² → x = 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.