A mass M is suspended from a light spring. An additional mass m is added, displaces the spring further by a distnce 'x'. Now the combined mass will oscillate with a period :

Question

$\begin {array} {1 1} (1)\;T=2\pi \sqrt{\large\frac{mg}{x(M+m)}} & \quad (2)\;T=2\pi \sqrt{\large\frac{(M+m)x}{mg}} \\ (3)\;T=\large\frac{2\pi}{3} \sqrt{\large\frac{mg}{(M+m)x}} & \quad (4)\;T=2\pi \sqrt{\large\frac{(M+m)}{mgx}} \end {array}$