(N/A) In the rotation of a rigid body about a fixed axis,every particle of the body moves in a circle which lies in a plane perpendicular to the axis and has its centre on the axis.
In the figure,the rotational motion of a rigid body is shown about the $Z$-axis of the frame of reference. Let $P_{1}$ be a particle of the rigid body,arbitrarily chosen and at a distance $r_{1}$ from the fixed axis. The particle $P_{1}$ describes a circle of radius $r_{1}$ with its centre $C_{1}$ on the fixed axis. The circle lies in a plane perpendicular to the axis.
Another particle $P_{2}$ of the rigid body is at a distance $r_{2}$ from the fixed axis. The particle $P_{2}$ moves in a circle of radius $r_{2}$ with its centre $C_{2}$ on the axis.
The circles described by $P_{1}$ and $P_{2}$ may lie in different planes,but both these planes are perpendicular to the fixed axis.
For any particle on the axis like $P_{3}$,$r_{3} = 0$. Any such particle remains stationary while the body rotates.
In the rotation of a spinning top,the axis may not be fixed as shown in the figure. Assume that the spinning top rotates at a fixed place.