Forces and Pressure.

1. Types of Forces:

1.1. Gravitational force, magnetic force and frictional force.

1.1.1. Gravitational force is something which pulls the object down to the Earth

1.1.2. Frictional force is something which occurs when two surfaces are in contact with each others. Frictional force is something which opposes frction

1.1.2.1. Advantages: Prevent us from slipping.

1.1.2.2. Disadvantages: causes wear and tear

1.1.2.3. Ways to reduce it: Lubricants, ball bearings.

1.1.3. Magnetic force is a force that is exerted from a magent to a magnetic material

1.1.3.1. Only magnets can repel each other.

2. Pressure is a force acting on per unit area. So when the pressure increases, the force increases and the area in contact decreases.

2.1. Eg. Elephant and the high heels. The high heels have a larger pressure as it has a smaller contact area the the elephant.

3. Calculating pressure:

3.1. Formula for pressure is force/area. The SI unit is Pascal. (Pa)

4. Pressure is a force acting per square centimetre/ metre

5. Effects of forces:

5.1. Change the shape and size of the object

5.2. Start a stationary object or stop a moving object

5.3. Speed up or slow down an object

5.4. Change the direction of the object.