Question

A body starts rotating from rest. Due to a couple of 20 Nm it completes 60 revolutions in one minute. Find the moment of inertia of the body.

Answer 1

T = 20 N m, n = 60 revolutions in 60 s = 1 r.p.s., t = 1 min = 60 s
Moment of inertia (I) = ?

Angular displacement θ = ωt = 2πnt
= 2π × 1 × 60
= 120 π rad

∴ Moment of inertia of the body is 95.48 kg m²