Question

Two discs, each of mass M and radius R is placed parallel to each other at a distance d about a common axis as shown in the figure. The moment of inertia of the system about $Y{Y}^{\prime }$ axis.

• A.
• B.
• C.
• D.

Answer 1

The correct option is C

Moment of inertia of a disc about its diameter, $I=\frac{M{R}^2}{4}$

Moment of inertia of a disc about $Y{Y}^1$ axis $I^1=I+M(\frac{d}{2}{)}^2$

$I^1=\frac{M{R}^2}{2}+\frac{M{d}^2}{4}$

$\therefore$ Moment of inertia of the system = $2I^1$

$=\frac{M{R}^2}{2}+\frac{M{d}^2}{2}$