Question

Moment of inertia of a body about a given axis is 1.5 kg m²
Initially the body is at rest. In order to produce a rotational kinetic energy of 1200 J, the angular acceleration of 20 rad/s² must be applied about the axis of rotation for a duration of:
(A) 2 s (B) 5 s
(C) 2.5 s (D) 3 s

Answer 1

Given moment of inertia ′I′=1.5kgm2

Angular Acc. "\alpha"=20 Rad/s^2

KE=21Iω2

1200=211.5×ω2

ω2=1.51200×2=1600

ω=40rad/s2

ω=ω0+αt

40=0+20t

t=2sec.