The moment of inertia of the body about an axis is 1.2 kg `m^(2)`. Initially the body is at rest. In order to produce a rotational kinetic energy of 1500J, an angualr acceleration of 25 `rad/s^(2)` must be applied about the axis for the duration of

Options

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

Answer

B

Explanation

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