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solid sphere (fig.6.6))
2 2
I  m  R (6.18)
5

Figure 6.6

thin-walled
hollow sphere

(fig6.7)
2 2
mI    R (6.19)
3

Figure 6.7

If the moment of inertia I of a body about an axis OO through
0
thecenter C of mass is known, then the moment of inertia I about any
other axis O Oparallel to the original one but displaced from it by

distance d is easily obtained by
means of a relation called the
parallel axis theorem or
Huygens–Steiner theorem

theorem:
2
I  I  md , (6.20)
0
where m is mass of body
This theorem is illustrated in

fig.6.8

Figure 6.8
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