Question

Seven identical coins are rigidly arranged on a flat table in the pattern shown below so that each coin touches its neighbors. Each coin is a thin disc of mass m and radius r. Note that the moment of inertia of an individual coin about an axis passing through centre and perpendicular to the plane of the coin is mr² /2 

The moment of inertia of the system of seven coins about an axis that passes through the point P (the centre of the coin positioned directly to the right of the central coin) and perpendicular to the plane of the coins is– 

(A) 55/2 mr²

(B)127/2  mr²

(C) 111/2 mr²

(D) 55 mr²

Answer 1

Correct :- (C)111/2 mr²

Explanation :-

By using parallel axis theorem, I = 111/2 mr²