A coin of mass m and radius r having moment of inertia I about the axis passing through its centre and perpendicular to its plane. It is beaten uniformly to form a disc of radius 2r. What will be the moment of inertia about the same axis?

A coin of mass m and radius r having moment of inertia I about the axi

1.	A coin of mass m and radius r having moment of inertia I about the axis passing through its centre and perpendicular to its plane. It is beaten uniformly to form a disc of radius 2r. What will be the moment of inertia about the same axis?
Answer» I 2I 4 I 16 I Solution :Moment of inertia of COIN of mass m and RADIUS r about the AXIS passing through its centre and perpendicular to its plane is `I = (mr^2)/(2) "" … (i)` Moment of inertia of formed disc about the same axis is `I. =(m(2r)^(2))/(2) = 4 ((mr^(2))/(2)) = 4I""` (USING (i))