A body of mass 'm' is rotated by means of a string along a verticle of radius 'r' with constant speed .The difference in tension when the body is at the bottom and at the top of the verticle circle is

Options

A. 6 mg
B. 4 mg
C. 2 mg
D. zero

Answer

C

Explanation

`T_("bottom")=mv^(2)/(r)+mg`
`T _("top")=(mv^(2))/(r)-mg`
`T_("bottom")-T_("top")=2mg`.