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 1500 J, an angular acceleration of 25 rad/`s^(2)` must be applied about that axis for a duration of

Options

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

Answer

B

Explanation

`I=1.2kgm^(2),E_(r)=1500J,`
`alpha=25` rad/`s^(2),omega_(1)=0,t=?`
As `E_(r)=1/2Iomega^(2)rArromega=sqrt((2E_(r))/l),`
`rArromega=sqrt((2xx1500)/(1.2))=50` rad/s
From `omega=omega_(0)+alphat`
`50=0+25t`, or t=2s