Question

A body of mass m is rotated in a vertical circle of radius R by means of light string. If the velocity of body is $\sqrt{gR}$ while it is crossing highest point of vertical circle then the tension in the string is:

• A. $2mg$
• B. $mg$
• C. $\frac{mg}{2}$
• D. Zero

Answer 1

The correct option is D Zero

At the highest point mg will act downward and Tension also in the same direction, then
$mg+T=\frac{m{\nu }^2}{R}$ ....... centripetal force

$mg+T=\frac{m\left(gR\right)}{R}$

$\Rightarrow T=0$