The moment of inertia of a body about a given axis is 1.2 kg `m^2`. Initially, the body is at rest. In order to produce a rotational kinetic energy of 6000 joule, an angular acceleration of 25 rad/`s^2` must be applied about that axis for a duration of

Options

A. 4 s
B. 2 s
C. 8 s
D. 10 s

Answer

A

Explanation

Rotational kinetic energy , `K_(R) = (1)/(2) I omega^(2) = (1)/(2) I alpha^(2) t^(2)`
Substituting the given values , we get
`6000 = (1)/(2) xx 1.2 xx (25)^(2) xx t^(2)` or `t^(2) = 16` or t = 4s