A highly rigid cubical block \Delta of small mass \(\mathbf{M}\) and side l is fixed rigidly onto another cubical block \(\beta\) of the same dimensions and of low modulus of rigidity \"\" such that the lower face of \hat{A} completely covers the upper face of \(\beta\) . The lower face of \(\beta\) is rigidly held on a horizontal surface. A small force \mathfrak{F} is applied perpendicular to one of the side faces of \Delta . After the force is withdrawn block \Delta executes small oscillations. The time period of which is given by