A spherical solid ball of 1,kg mass and radius 30,cm is rotating about an axis passing through its c

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6.System of Particles and Rotational Motion

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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

$910$

D

$45$

Solution

since $\mathrm{K}$$. E.$ of rotation $=\frac{1}{2} \mathrm{I} \omega^{2}, \mathrm{I}=\frac{2}{5} \mathrm{MR}^{2}$

$\therefore \quad \mathrm{K.} \mathrm{E} \cdot=\frac{1}{2} \times \frac{2}{5} \times 1 \times(.3)^{2} \times(50)^{2}=45 \mathrm{J}$

Standard 11

Physics

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