If a body is acted upon by a number of coplanar non-concurrent forces, if any

rotate about itself without moving

move in any one direction rotating about itself

be completely at rest

If a body is acted upon by a number of coplanar non-concurrent forces, if any

rotate about itself without moving

move in any one direction rotating about itself

be completely at rest

A smooth cylinder lying on its convex surface remains in unstable equilibrium.

Three forces acting on a rigid body are represented in magnitude, direction and line of action by the three sides of a triangle taken in order. The forces are equivalent to a couple whose moment is equal to twice the area of the triangle.

The principle of transmissibility of forces states that, when a force acts upon a body, its effect is minimum, if it acts at the centre of gravity of the body.

A smooth cylinder lying on a horizontal surface is in neutral equilibrium