Question

Four rod each of mass m from a square length of diagonal b rotates about its diagonal. Its moment of inertia is:-

Answer 1

By ll axis theorem

$\frac{M{L}^2}{12}+\frac{M{L}^2}{4}=\frac{M{L}^2}{3}$

there are 4 rods,So $4\ast 2\frac{M{L}^2}{3}$

Diagonal is mutually perpendicular $I+I=4\frac{M{L}^2}{3}$

So,$I=\frac{2}{3}M{L}^2$