Question

A plank P is placed on a solid cylinder S, which rolls on a horizontal surface. The two are of equal mass. There is no slipping at any of the surfaces in contact. The ratio of kinetic energy of P to the kinetic energy of S is:

• A. 1:1
• B. 2 : 1
• C. 8 : 3
• D. 11 : 8

Answer 1

The correct option is C

8 : 3

$KEofP=\frac{1}{2}m(2v{)}^2=2m{v}^2$

$KEofS=\frac{1}{2}m{v}^2+\frac{1}{2}I{\omega }^2=\frac{3}{4}m{v}^2\Rightarrow \frac{KEofP}{KEofS}=\frac{8}{3}$