In rotation of a rigid body about a fixed axis is that in which:
- Aevery particle of the body moves in a circle, which lies in a plane perpendicular to the axis and has its centre on the axis.
- Bevery particle of the body moves in an ellipse, which lies in a plane perpendicular to the axis and has its focii on the axis.
- Cparticles close to the axis have larger velocities.
- Devery particle of the body moves at the same speed.


