Hi friends the problem is - https://fbcdn-sphotos-d-a.akamaihd.net/hphotos-ak-prn1/30370_2656498989013_1471109032_n.jpg Attempt - friends as per the question I am trying to get the acceleration- displacement equation for this problem. So I am using F = - (dU / dx) Differentiating Potential energy function w.r.t. x I get, F = - (2a + 4b .x3) But F = mass. acceleration so, acceleration = - (2a/m + 4b/m x3) Now I am sticking here that how to proceed further to get the result like, acceleration = - ω2 . x Please friends help me in solving this Problem. Thank you all in advance.