Question

Four identical thin rods each of mass M and length l, from a square frame. Moment of inertia of this frame about an axis through the centre of the square and perpendicular to its plane is :

Answer 1

Answer:

Moment of inertia for the rod AB rotating about an axis through the midpoint of AB perpendicular to the plane of the paper is Ml2/12. Moment of inertia about the axis through the centre of the square and parallel to this axis, For all the four rods, I = 4/3 MI2. /four-identical-thin-rods-each-of-mass-m-and-length-l-form-a-square-frame

Answer 2

1) moment of inertia of a rod passing through its centre and perpendicular to it is ml2/12.

2) Now the centre is located at l/2 from one rod, so apply parallel axis theorem MI of one rod = ML2/3

3) For 4 rods MI = 4ML2/3