Q: A ring of mass m = 10kg can slide through a vertical rod without friction. It is connected with a spring of force constant k = 100 Nm-1. The relaxed length of spring is 4m. The ring is displaced 3m as shown in figure and released. The velocity of ring when spring becomes horizontal.
(a) 5ms-1
(b) 15ms-1
(c) 10ms-1
(d) 12ms-1
Ans: (c)