Two identical springs are attached to a small  block P. The other ends of the springs are  fixed at A and B. When P is in equilibrium  the extension of top spring is 20 cm and  extension of bottom spring is 10 cm. The   period of small vertical oscillations of P  about its equilibrium position is (use g = 
9.8 m/ $s^2$)





$$\begin{gathered} a. \frac{2\mathrm{\pi }}{7} sec \\ b.\frac{\mathrm{\pi }}{7} sec \\ c.\frac{2\mathrm{\pi }}{5}sec \\ d.none of these \end{gathered}$$

Two identical springs are attached to a small  block P. The other ends of the springs are  fixed at A and B. When P is in equilibrium  the extension of top spring is 20 cm and  extension of bottom spring is 10 cm. The   period of small vertical oscillations of P  about its equilibrium position is (use g = 
9.8 m/ $s^2$)





$$\begin{gathered} a. \frac{2\mathrm{\pi }}{7} sec \\ b.\frac{\mathrm{\pi }}{7} sec \\ c.\frac{2\mathrm{\pi }}{5}sec \\ d.none of these \end{gathered}$$