A body whose moment of intertia is `3 kg m^(2)` is at rest. It is rotated for `20 s` with a moment of force `6 N-m`. Find angular displacement of the body. What is work done ?

Explanation

Here, `I = 3kg m^(2), omega_(1) = 0, t = 20 s`.
Moment of force, `tau = 6 N-m, theta = ?, W = ?`
As `tau = I alpha, alpha = (tau)/(I) = (6)/(3) = 2 rad s^(-2)`
Angular displacement, `theta = omega_(1)t + (1)/(2) alpha t^(2)` ltbr. `= 0 + (1)/(2) xx 2 (20)^(2) = 400 rad`.
Work done, `W = tau theta = 6 xx 400 = 2400 J`