Question

when a body is under pure rolling the fraction of its total kinetic energy which is purely rotational is 2/5 .identify the body

Answer 1

hello friend . here is ur answer in the above given attachment

Answer 2

Answer:

Hollow sphere

Explanation:

In this type of question calculate the expression for moment of inertia I and that helps in identifying the body

Rotational KE = 1/2Iω²  

Translational KE = 1/2Mv²      

∴ Total KE=1/2Iω² + 1/2Mv²

Given,  

$\frac{2}{5}$ = $\frac{Rotational K.E.}{Total KE}$        

For pure rolling put v=ωR    (or)   $\frac{2}{5}$ =   $\frac{ Iw^{2} }{Iw^{2}+Mw^{2}R^{2} }$

∴I=2/3MR²

So, the rolling body is hollow sphere.