The formula to calculate the kinetic energy of a particle executing SHM is given by
K=21mω2(A2−x2)...(1)
Substitute 0 for x into equation (1) to obtain the kinetic energy at the mean position.
K==21mω2(A2−02)21mω2A2
Substitute Afor x into equation (1) to obtain the kinetic energy at the end points.
K==21mω2(A2−A2)0
Hence, the variation can be shown as follows-




