A circular disc of radius r and mass m rotates about the axis passing through the centre and perpendicular to its plane. What will if rotational kinetic energy?

Options

A. `(1)/(4)mromega^(2)`
B. `(1)/(2)mromega^(2)`
C. `(1)/(4)mr^(2)omega^(2)`
D. `(1)/(2)mr^(2)omega^(2)`

Answer

C

Explanation

Rotational kinetic energy = `(1)/(2)Iomega^(2)`
`=(1)/(2)xx(mr^(2))/(2)xxomega^(2)`
`=(1)/(4)mr^(2)omega^(2)`