1. The problem statement, all variables and given/known data 2. Relevant equations 3. The attempt at a solution Initially the rod is in rotational equilibrium , so net torque about CM is zero . From torque equation about CM , we get Tension T in the left string = Force F (kx) in the spring Doing a force balance gives us T+F=Mg 2F=Mg F=Mg/2 Now when the string is cut , force equation in vertical direction is Mg - F = Ma Torque equation about the CM is F(L/2) = (ML2/12)α F = Mg/2 since force exerted by spring remains same just after right string is cut . Using value of F in the above two eqs gives a = g/2 and α = (3g/L) Have I approached it correctly ?