Explanation

(b) Angular velocity is given by
$\omega =$600 rotation/min
$= \frac{600 \times 2\pi}{60}rads^{- 1} = 20\pi\ rads^{- 1}$
Kinetic energy of coin which is due to rotation and translation is
$K = \frac{1}{2}\ I\omega^{2} + \frac{1}{2}mv^{2}$
$= \frac{1}{2} \times \frac{1}{2}mr^{2}\omega^{2} + \frac{1}{2}m(\omega r)^{2}$
$= \frac{1}{4} \times 4.8 \times (1)^{2}(20\pi)^{2} + \frac{1}{2} \times 4.8 \times (20\pi \times 1)^{2}$
$= 480\pi^{2} + 960\pi^{2} = 1440\pi^{2}J$