Moment of inertia of a body about a given axis is `1.5 kg m^(2)`. Intially the body is at rest. In order to produce a rotational kinetic energy iof 1200 J, the angular acceleration of 20 rad/`s^(2)` must be applied about the axis for a duration of

Options

A. 5s
B. 25s
C. 2s
D. 3s

Answer

C

Explanation

`alpha = 20 rad/sec^(2) , omega = omega_(0) + alpha t, omega = 20 t, 1/2 I omega^(2) = 1200`
`1/2 xx 1.5 xx (20t^(2)) = 1200, t=2` sec.