Moment of inertia of a body about a given axis is 1.5 k g m 2 . Initially the body is at rest. In order to produce a rotational kinetic energy of 1200 J , the angular acceleration of 20 r a d / s 2 must be applied about the axis for a duration of:

Step-by-step solution

We know that, Rotational kinetic energy, K = 1 2 I ω 2 ⇒ 1 2 I ω 2 = 1200 ⇒ 1 2 × 1 .5 × ω 2 = 1200 ⇒ ω = 40   rad   s - 1 We also know that, ω = α t ⇒ t = 40 20 = 2   s