The rotational kinetic energy of a solid sphere of mass 3 kg and radius `0.2 m` rolling down an inclined plane of height 7 m is :

Options

A. 42 J
B. 60 J
C. 36 J
D. 70 J

Explanation

`mgh =(1)/(2) [ (7)/(5) mR ^(2) ] omega ^(2) " "...(i)`
`KE _(rot) = (1)/(2) [ (2)/(5) mR ^(2) ] omega ^(2) " "..(2)`
by Eqs. (1) and (2)
`KE _(rot ) = (2)/(7) mgh = (2)/(7) xx 3 xx 10 xx 7 = 60 J`