A solid sphere of mass M and radius R has a moment of inertia about an axis tangent to its surface is given by formula …………..

Options

A. `(2)/(5)MR^(2)`
B. `(7)/(5)MR^(2)`
C. `(2)/(3)MR^(2)`
D. `(5)/(3)MR^(2)`

Answer

B

Explanation

Moment of inertia of solid sphere about an axis passing through its centre `I_(c )=(2)/(5)MR^(2)`
From parallel axis theorem, moment of inertia about axis tangential to surface,
`I=I_(c)+Md^(2)`
`=(2)/(5)MR^(2)+MR^(2) [because d=R]`
`therefore I=(7)/(5)MR^(2)`