Three identical solid discs, each of mass M and radius R, are arranged as shown in figure. The moment of inertia of the system about an axis AB will be

Options

A. `(11)/(4)MR^(2)`
B. `(15)/(4)MR^(2)`
C. `(13)/(4)MR^(2)`
D. `(21)/(5)MR^(2)`

Answer

B

Explanation

`I=I_(1)+I_(2)+I_(3)`
`=(5)/(4)MR^(2)+(5)/(4)MR^(2)+(5)/(4)MR^(2)=(15MR^(2))/(4)`.