# Gravitation

• How to know whether a body is in stable or unstable equilibrium?

• @srinidhi-v
A body is in stable equilibrium if it is able to return to its position when slightly disturbed. Failure to do so denotes unstable equilibrium.

Here, if we disturb the mass at point O, net force along B will increase. Hence B will attract the point mass towards itself. The point mass will not come back to the original position of it. Thus unstable.

• @sarthak-basak Should we have to calculate that?

• @srinidhi-v
No calculation. It is theory. It is conceptual question.

• @sarthak-basak Without calculations how can u say that it is stable or unstable?

• @srinidhi-v

1. Disturb the position of the point mass O
2. If you slightly move the mass towards A, distance between A and O will decrease, thus force between A and O will increase. In that case, A will attract the mass O towards itself. Then O will not come back in it's own position.
3. Same thing with B. If you slightly move the mass towards B, distance between B and O will decrease, thus force between B and O will increase. Thus O will move towards B and Never returns.
4. Since in the both cases we have seen that O never return to the original position, conclusion : unstable equilibrium

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