Question

A uniform circular disc of radius 'R' with a concentric circular hole of radius $\frac{R}{2}$ rolls on a horizontal plane. The fraction of its total energy associated with its rotational motion is

• A. $\frac{1}{4}$
• B. $\frac{5}{13}$
• C. $\frac{1}{2}$
• D. $1$

Answer 1

The correct option is B $\frac{5}{13}$

$I=\frac{5}{8}m{r}^2$
$\frac{R.K.E}{T.E}=\frac{1}{1+\frac{R^2}{K^2}}=\frac{1}{1+\frac{8}{5}}=\frac{5}{13}$