Question

Point masses of 1,2,3 and 10 kg are lying at the point (0 0) (2 0) (0 3 )(- 2 - 2) respectively. In x-y plane, the moment of inertia of the system about y axis will be in Kg metre2

Answer 1

Moment of inertia of the system is the sum of moment of inertia of each point masses.
moment of inertia of point mass$,I=M{R}^2$

1) point mass of 1 kg which is at a distance of 0 units from y axis.Its moment of inertia about y axis is zero,because R=0.
2) point mass of 2 kg which is at a distance of 2 units from y axis. I=2*2^2=8.kg m^2.
3) point mass of 3 kg which is at a distance of 0 units from y axis.so moment of inertia about y axis is zero,because R=0.
4) point mass of 10 kg is at a distance of 2 units from y axis.I=10*2^2=40kg m^2.
total moment of inertia of the system is 0+8+0+40=48 kg m^2.
Hope you understand .all the best