Ravinder, a student of class XI. He had two identical spheres one hollow and the other solid. He told his younger brother that he had the power to spin these two spheres with different speeds. His told his younger brother that this is a magic However, Sham was also standing there. Sham told the younger brother of Ravinder it is not magic. He can also do the same. (i) How can two identical spheres, one hollow and the other solid spin with different speed?

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Solution

Dear Student,

In case of rotation if we supply same power to the sphere's then rotational Kinetic energy will be

$K = \frac{1}{2} I ω^{2}$
For solid and hollow sphere moment of inertia are different hence for the same power angular velocities will be different ,So sphere will rotate with different angular speed.

Regards.

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