A 2 kg stone at the end of a string 1 m long is whirled in a vertical circle at a constant speed of 4 m/s. The tension in the string will be 52 N when the stone is
(Take g = 10 m/s2 )
(A) at the top of the circle
(B) at the bottom of the circle
(C) halfway down
(D) at any position other than that in (A), (B) and (C)
