7.1 The diagram below depicts a part of an instrument made to measure earthquakes. A rigid rod of mass \(M\), length \(l\)  is constrained to only rotate about a pivot \(O\) at its bottom. On the top of the rod sits a ball of mass , connected by two light springs of spring constant to fixed walls. In its equilibrium position, the rod is perfectly vertical, and both springs are unstretched. Now we give it a slight impulse to kickstart small oscillations about its equilibrium position. What conditions must be satisfied so that the resulting oscillations are simple harmonic? Determine the period of small oscillations.