Formulae for moments of inertia
The list that follows gives the
more important moments of inertia for some common simply shaped objects.
(a) Uniform thin rod about one
end
Moment of inertia (I) = mL2/3
(b) Uniform thin rod
about the middle
Moment of inertia (I) = mL2/12
(c) Circular disc about the centre
Moment of inertia (I) = mr2/2
(d) Cylinder
about the axis of symmetry:
(i) solid cylinder
Moment of inertia (I) = mr2/2
(ii) hollow cylinder
Moment of inertia (I) = mr2
(e) Sphere about a diameter
Moment of inertia (I) = 2mr2/5
(f) a ring of
negligible width about the centre
Moment of inertia (I) = mr2
