Q.

A body is executing simple harmonic motion with frequency n, the frequency of its potential energy is               [2021]

1 4n  
2 n  
3 2n  
4 3n  

Ans.

(3)

The equation for the S.H.M. is

y=Asinωt=Asin(2πnt)                                            ...(i)

where, A is amplitude, ω is angular frequency and y is displacement at time t.
The formula of potential energy is

U=12kA2sin2ωt

U=12kA2(1-cos2ωt2)=12kA2[1-cos2π(2n)t2]                         ...(ii)

                                                                                   (sin2θ=1-cos2θ2)  

From eqn. (i) and (ii), we get

Frequency of potential energy = 2n