MCQ
A spherical solid ball of $1\,kg$ mass and radius $30\,cm$ is rotating about an axis passing through its centre with an angular velocity of $50\,radian/s$ . The kinetic energy of rotation is ......... $J$.
- A$4500$
- B$90$
- C$910$
- ✓$45$
✓
Answer
Correct option: D.
$45$
d
since $\mathrm{K}$$. E.$ of rotation $=\frac{1}{2} \mathrm{I} \omega^{2}, \mathrm{I}=\frac{2}{5} \mathrm{MR}^{2}$
since $\mathrm{K}$$. E.$ of rotation $=\frac{1}{2} \mathrm{I} \omega^{2}, \mathrm{I}=\frac{2}{5} \mathrm{MR}^{2}$
$\therefore \quad \mathrm{K.} \mathrm{E} \cdot=\frac{1}{2} \times \frac{2}{5} \times 1 \times(.3)^{2} \times(50)^{2}=45 \mathrm{J}$
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