Question

Seven identical circular planar discs, each of mass M and radius ft are welded symmetrically as shown in the figure. The moment of inertia of the arrangement about the axis normal to the plane and passing through the point P is

(a) 19/2 MR²

(b) 55/2 MR²

(c) 73/2 MR²

(d) 181/2 MR²

Answer 1

Correct Option (d) 181/2 MR²

Explanation: 

First we found moment of inertia (MI) of system using parallel axis theorem about centre of mass, then u)e use it to find, moment of inertia about given axis.

Moment of inertia of an outer disc about the axis through centre is