# Physics P3 Revision notes

All parts in red are higher topics

- Created by: Bhavik
- Created on: 13-05-11 11:36

First 328 words of the document:

Physics revision notes

Physics Revision notes

The force applied on something has an effect on the turning effect.

The long handled spanners are better than short handled ones because they have a

larger moment.

Increasing the size of the force or using a longer length both increase the moment.

A crowbar is a lever. The weight is called a load. The force applied is the effort and the

point about which the crowbar turns it the pivot.

Moment (Newton Metres) = Force (Newtons) x Perpendicular distance from the

pivot to the line of action of the force

The centre of mass of an object is the point where its mass may be thought to be

concentrated.

A rectangle has the centre of mass where the two lines of symmetry meet

The same for an equilateral triangle.

A seesaw is an example in which the clockwise and anti clockwise moments might

balance each other out.

W1d1 = W2d2

The seesaw is an example of the principle of moments. This states that an object in

equilibrium:

The sum of all the clockwise moments about any point = the sum of all the

anticlockwise moments about that point

EG. If W2 = 4N and D1 = 0.25m and D2 = 0.2 m

Then W1 = W2d2/d1 = 4x0.2/0.25 = 3.2 N

If the centre of mass is outside the base of an object then it will topple over.

3 examples of things tested for stability are Tractors, Buses and high chairs for

babies.

An object moving at a constant speed at any instant: The object's velocity is directed

along a tangent to the circle, its velocity changes direction as it moves around, the

change of velocity is towards the centre of the circle. Therefore the object

accelerates continuously towards the centre of the circle.

Bhavik BarochiaPage 1

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