One end of a spring of spring constant $80 \mathrm{Nm}^{-1}$ and unstretched length of $30 \mathrm{~cm}$ is…
One end of a spring of spring constant $80 \mathrm{Nm}^{-1}$ and unstretched length of $30 \mathrm{~cm}$ is fixed at point $\mathrm{A}$ and the other end of the spring is fitted with a smooth ring of mass $300 \mathrm{~g}$ as shown in the figure. The ring is allowed to slide on a horizontal rod fixed at a height of $40 \mathrm{~cm}$. Initially the spring makes an angle of $60^{\circ}$ with the vertical and the system of spring and ring is released from rest. The speed of the ring when the spring becomes vertical is ____ $\mathrm{ms}^{-1}$.
