Question

A disc of mass M has its radius of gyration K about a
diameter axis. The moment of inertia of the disc
about that axis is
a)1/2 MK^2
b)3/2MK^2
c)1/4 MK^2
d) MK^2
​

Answer 1

here the moment of inertia of disc is 1/2MR² /2

= 1/4MR²

Explanation:

moment of inertia of disc

= 1/4MR²

equating with MK²

1/4MR² = MK²

so K = 1/4R²

so we got the new value of K

so the final equation 1/4MK².

here the disc is rotating about

x or y axis. not in z axis. so we apply perpendicular axis theorem.