Question

Four identical rods, each of mass m and length l, are joined to form a rigid square frame. The frame lies in the xy plane, with its centre at the origin and the sides parallel to the x and y axes. Its moment of inertia about

(a) the x-axis is 2/3 ml²

(b) the z-axis is 4/3 ml²

(c) an axis parallel to the z-axis and passing through a corner is 10/3 ml²

(d) one side is 5/2 ml² 

Answer 1

Correct Answer is: (a, b, c, & d)

Answer 2

The moment of inertia of one rod about the center of the square frame using parallel axis theorem is
1/12 mI^2 + 1/4 mI^2 = 1/3mI^2
1/3mI^2 + mI^2 = 4/3mI^2 along z axis