- To an object at rest.
- No tendency to rotate about its axis of rotation when at rest
- Axis of rotation pass through centre of gravity.
- Uneven mass distribution around rotational axis in a single plane.
- Refers to a rotating object
- Dynamically unbalance axis of rotation will have tendency to wobble about its centre of mass.
- Axis of rotation should pass through centre of gravity and should be principle axis of inertia.
- Unevenness in two different planes.
- Done by adding counter weights