Example:find the moment of inertia of a hoop when the axis is the diameter of the hoop. Solution: We choose the coordinate system as the figure Jeft,by symmetry,we have: Jx=Jy Therefore, =4+52X∂Example: find the moment of inertia of a hoop when the axis is the diameter of the hoop. Solution: We choose the coordinate system as the figure left, by symmetry, we have: Therefore