MCQ
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 $..........ms ^{-1}$.
- ✓$40$
- B$38$
- C$37$
- D$36$
✓
Answer
Correct option: A.
$40$
a
$KE =\frac{1}{2} mv ^2+\frac{1}{2} I \omega^2$
$KE =\frac{1}{2} mv ^2+\frac{1}{2} I \omega^2$
$2240=\frac{1}{2} 2( v )^2+\frac{1}{2} \frac{2}{5}(2) R ^2 \cdot\left(\frac{ v }{ R }\right)^2$
$2240= v ^2+\frac{2}{5} v ^2$
$\Rightarrow v =40\,m / s$
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