Question

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

Answer 1

a) Rotational kinetic energy, `1/2 Iomega^(2)`
According to question, `1/2Iomega^(2)`=1500
`1/2l(alphat)^(2) = 1500 `
`(1.2) xx (25)^(2) xx t^(2) = 3000`
`1.2 xx 625 xx t^(2) = 3000`
`t^(2) = (3000/(1.2 xx 625)` = 4
`t=2s`