Answer: x = A/2.
- A x = A
- B x = A/4
- C x = A/√2
- D x = A/2
Correct answer: D. x = A/2
Explanation: PE = (1/2)kx<sup>2</sup> and total E = (1/2)kA<sup>2</sup>. Setting PE = E/4 gives x<sup>2</sup>/A<sup>2</sup> = 1/4, so 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.