Question

If the total kinetic energy of a rolling solid cylinder is $24J$ then its rotational kinetic energy is:

• A. $8J$
• B. $12J$
• C. $16J$
• D. $20J$

Answer 1

The correct option is A $8J$

$TKE=24J.$ (total kinetic energy)
$\frac{KE{)}_T}{KE{)}_R}=\frac{\frac{1}{2}m{V}^2}{\left(\frac{1}{2}\frac{m}{2}{R}^2\frac{V^2}{R^2}\right)}=\frac{2}{1}$
Translational and Rotational are divided in 2:1 ratio of total KE.
$KE{)}_R=\frac{1\times 24}{2+1}$
$=8J.$