# Moment of a force

1. Jul 16, 2011

I just read that moment of a force about a point is the turning or twisting effect of the force about that point.

Moment of a force= magnitude of force*perpendicular distance between the line of action of force and the point

So how can force affect that point without even coming in contact with it?

2. Jul 16, 2011

### I like Serena

It doesn't.

Consider a hollow body and take a moment relative to a point within the body.
The moment makes the body turn, but the point it's relative to is unaffected.
It is just a point of reference.

3. Jul 16, 2011

### sophiecentaur

The principle of moments only applies to rigid bodies like levers, wheels etc.
But you can calculate the actual moments about any point you like. The force needn't actually "affect" the point.

4. Aug 21, 2011

### shri4physics

yes,
it doesn't matter
where the point lies but it maters only whether the point is in line of action of that force or not?
and,
it's similar case is our earth is rotating right about it's line of action continuously so, the rotational force do exist continuously and the particles of earth(us) also experiencing thee force.