A Stone Is Released from Rest at a Height H $\sqrt { 2 }$

Multiple Choice

A stone is released from rest at a height h at the left side of a loop-the-loop,as shown in the figure.There is no appreciable friction force exerted by the track or by air resistance.If the radius of the loop is R,what is the minimum height h for which the stone will not fall off the track at the top of the loop?

A) 3.5 R
B) 2.5 R
C) 2.0 R
D) $\sqrt { 2 }$ R
E) 3.0 R