Four spheres A, B, C, D, each of mass m and diameter 2 a are placed with their centres at die four corners of a square of side b. What is the moment of inertia of the system about any side of the square ?

Answer

`8/5 ma^(2) + 2mb^(2)`

Explanation

M.I of sphere A and D about AD `=(2//5)ma^(2) xx 2 = (4//5) ma^(2)`. MI. of B and C about BC `=(4//5) ma^(2)` M.I. of B and C about AD `=(4//5)ma^(2) + 2 mb^(2)`. M.I. of system about AD `=(8//5) ma^(2) + 2mb^(2)`