# Forces

A bed has springs in it to make it more comfortable
It is difficult to lift up a large lump of rock
The elastic in a catapult can fire a stone
Two magnets can be made to push each other apart
Small pieces of paper will stick to a charged comb
Brakes can be used to slow down a bike
A gust of wind can blow you over!
The Moon moves in an orbit round the Earth
A ball can be made to move fast if it is hit by a bat

These effects are a few examples of different types of FORCES.

A FORCE is just a PUSH or a PULL on something

A force can do different things to an object depending on how it acts:
(a) PUSH it - a parent pushing a pram
(b) PULL it - a tractor pulling a trailer
(c) SQUASH - lying on a soft bed
(d) STRETCH it - a catapult elastic
(e) TURN it - a door handle
(f) SLOW it DOWN - a car braking
(g) SPEED it UP - a sprinter starting a race

There are four main types of force that you will meet in your everyday lives:
(a) GRAVITY – this is the pull of the Earth on you and is what makes any object have weight and feel heavy.
(b) MAGNETISM – the force between two magnets
(c) ELECTRICAL – the force between static electric charges that makes your hair stand on end if you comb it vigorously
(d) MECHANICAL – the force in your muscles (like the weightlifter) or in a machine

STUDENT INVESTIGATIONS
These simple experiments will help you to understand a little more about forces.
1. Stretch the rubber band
2. Squash the large spring and then let it go
3. Bend the piece of foam rubber
4. Squeeze the piece of plasticine
5. Blow the polystyrene ball along the bench with the straw

Describe what you see in each experiment
Devise and carry out an experiment to measure the stretchability of socks or tights.

PROBLEMS
1. What different forces are used in the examples at the beginning of this section?
You can choose from the following list:
electrical, wind, muscular, gravitational, elastic, magnetic

2. Give another example of each of the six types of force in question one.

© Keith Gibbs 2011