Question

A solid cylinder of mass $0.1kg$ and radius $0.025metre$ is rolling on a horizontal smooth table with uniform velocity of $0.1m{s}^{-1}$. Its total energy will be :

• A. $7.5\times {10}^{-2}Joule$
• B. $7.5\times {10}^{-3}Joule$
• C. $7.5\times {10}^{-4}Joule$
• D. $0.07\times {10}^{-4}Joule$

Answer 1

The correct option is C $7.5\times {10}^{-4}Joule$

Moment of inertia of a solid cylinder is $\frac{m{r}^2}{2}$
Total energy=$\frac{1}{2}m{v}^2+\frac{1}{2}\frac{m{r}^2}{2}\frac{v^2}{r^2}$
=$\frac{3}{4}m{v}^2$
=$0.75\times 0.1\times {0.1}^2$
=$7.5\times {10}^{-4}J$