# AQA Unit 3 Physics

AQA P3 GCSE HIGHER TIER Revision

I have still to upadate it with information on making stars but I will do it soon! Hope this is useful!

- Created by: Hajani Prem
- Created on: 26-05-12 16:39

First 316 words of the document:

The Turning Effect of Forces

Forces have a turning effect. They tend to make objects turn around a fixed point called a pivot or a fulcrum. The

turning effect of a force about a pivot is called its moment.

Moment (Nm) = force (N) x perpendicular distance from pivot (m)

The perpendicular distance is basically the distance from the pivot to the line of force. It has to be

900 for the correct value.

An object will be in balance if:

Sum of anticlockwise moments = sum of clockwise movements

Centre of Mass

The centre of mass is the point where the whole of the weight of the

object appears of act. It can be found by drawing lines of symmetry (if the

object is rectangular or symmetrical) and finding the point which all the

lines intersect, or, for an irregular shape, by suspending it freely by a

point on its edge and using a plumb line to indicate the space directly

vertical to the point. The centre of mass is always vertically below the

pivot so you can work out the centre of mass by drawing a point

somewhere in the middle of the plumb line, or suspending the object at

different points on its edge and finding out where all the lines intersect.

Objects with a low centre of mass and a wide base are stable as it is

difficult to knock over.

Parallel Forces Acting on a Plane

That's basically using the principle of moments (clockwise moment = anticlockwise moment) to find out whatever

the question asks.

Forces Acting on a Beam

The upward forces on a light beam, supported at its ends, vary with the position of a heavy object placed on the

beam.

For example(s):

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