Question

Find the moment of inertia of a plane rectangular lamina of length 20 cm breadth 10cm and mass 500 g about an axis passing through its centre and perpendicular to its plane.

• A. 0.002083 $kg{m}^2$
• B. 0.001083 $kg{m}^2$
• C. 0.003083 $kg{m}^2$
• D. 0.004083 $kg{m}^2$

Answer 1

The correct option is A

0.002083 $kg{m}^2$

m=500gm =0.5kg, l=20cm=0.2m; b=10cm=0.1m
Moment of inertia of the rectangular lamina about an axis passing through its centre and perpendicular to its plane is
$I_0=m\left[\frac{l^2+b^2}{12}\right]=0.5\left[\frac{{0.2}^2+{0.1}^2}{12}\right]=0.002083kg{m}^2$