Question

A particle executes simple harmonic motion of amplitude A. At what distance from the mean position is its kinetic energy equal to its potential energy?

(a) 0.51A

(b) 0.71A

(c) 0.61A

(d) 0.81A

This question was addressed to me in unit test.

Question is from Wave Motion in section Waves of Engineering Physics I

Answer 1

Correct answer is (b) 0.71A

The best I can explain: Ek=Ep

1/2 k(A^2-y^2)=1/2×ky^2

y=±A/√2

y=±0.71A.