Question

A circular disc whose radius is 0.5 m and mass 25 kg is rotating on its axis with 120 revolutions/minute. Calculate the moment of inertia of the disc and rotational kinetic energy.

Answer 1

Given Radius of the disc, R = 0.5 m;
Mass of the disc, M = 25 kg; l = ?; E_r = ?;
Frequency = 120 rev/min = \(\frac{120}{60}\) rev/s = 2 Hz
∴ Angular velocity, ω = 2πn = 2π × 2 = 4π rad/s
Therefore, moment of inertia of the disc about its own axis,