Forces

1. effects of forces

1.1. stop a moving object

1.2. slow down a moving object

1.3. change the shape or size of an object

1.4. change the direction of a moving object

1.5. start an object moving

2. how to measure a force

2.1. force meters

2.1.1. compression spring balance

2.1.2. extension spring balance

3. frictional force

3.1. useful for brakes, nails and a runner

3.2. problem, worn out tyres, slows down a cyclist

3.3. ways to reduce friction

3.3.1. smooth surface

3.3.2. ball bearings

3.3.3. kuvricants

3.3.4. stream-lined shape

4. magnetic force

4.1. a magnet attracts objects made of iron and steel

4.2. like poles of a magnet repel

4.3. unlike poles of a magnet attract

4.4. example: maglev train, but it still encounters air resistance. As there is no friction between the train and the track, the train will go faster

5. gravitational force

5.1. it is a force which pulls objects towards the earth also known as gravity

5.2. weight

5.2.1. it is a force of gravity pulling on the object so the unit is Newton(N)