Question

A frictionless track $ABCDE$ ends in a circular loop of radius $R$. A body slides down the track from point $A$ which is at height $h=5cm$. Maximum value of $R$ for the body to successfully complete the loop is :-

• A. $5cm$.
• B. $2cm$.
• C. $\frac{10}{3}cm$
• D. $\frac{15}{4}cm$

Answer 1

The correct option is B $2cm$.

From the conservation of energy,

$mgh=\frac{1}{2}m{v}^2$

$v=\sqrt{2gh}$

The condition for completing the loop is given as,

$\sqrt{2gh}=\sqrt{5gR}$

$R=\frac{2\times 5}{5}$

$=2cm$

Thus, the maximum value of $R$ for the body to successfully complete the loop is $2cm$.