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 ____ \(\mathrm{ms}^{-1}\).

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.