Question 434: Centre of Mass and Rotational Motion

Question

A solid sphere of mass 2 kg is making pure rolling on a horizontal surface with kinetic energy 2240 J. The velocity of centre of mass of the sphere will be _______ ms$$^{-1}$$.

Accepted Answer

$\frac{1}{2} m v_{\mathrm{cm}}^{2}+\frac{1}{2} 	imes \frac{2}{5} m R^{2} 	imes \frac{v_{\mathrm{cm}}^{2}}{R^{2}}=2240 \mathrm{~J}$
$$
\begin{aligned}
& \frac{7}{10} m v_{\mathrm{cm}}^{2}=2240 \\
& v_{\mathrm{cm}}=\sqrt{\frac{2240 	imes 10}{7 	imes 2}}=40 \mathrm{~m} / \mathrm{sec}
\end{aligned}
$$

Centre of Mass and Rotational Motion

A solid sphere of mass 2 kg is making pure rolling on a horizontal surface with kinetic energy 2240 J. The velocity of centre of mass of the sphere will be _______ ms$^{-1}$.

Choose the correct answer: