# Physics unit 3 Topic 1

Physics Unit 3 Topic Unit 3

How do forces have a turning effect?

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• Created by: Dom
• Created on: 02-02-11 18:32

## Forces

Forces acting on the body are balanced in the sense that they do not cause the body to change speed but they can still make the body turn.

Turning effect of a force is called the momentum.                                                  The size of the momentum is given by the equation:

Moment = Force x Perpendicular distance

(Nm) = (N) x (m)

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## Center of Mass

The center of mass of a body is the point at which the mass of the body may be thought to be concentrated.

• Oftern lies allong the objects axis of symmetery.
• In a sphere and a cube these ruels mean that the C of M lie in their centers.
• An object does not turn if the pivot passes through the center of mass if not, the object will turn.
• A suspended object will always come to rest with its center of mass directly below the point at which it is supported.
• Experiment = A piece of flat card suspended on a pivot, a line is drawn over a hung plumbline. Where the lines cross is the objects center of mass.

ACM = CM

Anti clockwise moment = Clockwise moment

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