Single Choice

A disc of radius $$R$$, is cut from a disc of radius $$R_{2}$$ as shown in figure. if the disc left has mass $$M$$ then find the moment of inertia of the disc left about an axis passing through its centre and perpendicular to its plane

A$$\dfrac {M}{2}(R^{2}_{2}-R^{2}_{1})$$
B$$\dfrac {M}{6}(R^{2}_{2}-R^{2}_{1})$$
C$$M\dfrac {R^{2}+R_{1}^{2}}{2}$$
Correct Answer
D$$\dfrac {MR^{2}_{2}}{2}$$

Solution

If there is complete Disc then we know
Iabout axis=
MR2
2



Now, R1 part is removed and having mass M of the remaining part

Iabout axis=
MR
2
2
2

−
MR
2
1
2




M
2

(R
2
2
−R
2
1
)

SIMILAR QUESTIONS

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