1. What is pressure?
1.1. amount of force exerted per unit area
1.2. Uses of high pressure: Increase force, decrease area [E.g.] -sharp knife (blade has small area, so with the same force it can produce a high pressure. -sharp nails -spikes on soccer shoes Uses of low pressure: Less force, more area [E.g.] -skiing -camel
2. Decreasing Pressure
2.1. Pressure decreases when area increases or the force decreases.
3. Types of Forces
3.1. Gravitational Force
3.1.1. -Exists between any two objects -The greater the force of gravity pulling an object, the heavier the object. -The weight of an object depends on the force of gravity pulling on that object.
3.2. Frictional Force
3.2.1. Positive effects of friction: -enable us to walk -hold things Negative effects of friction: -car tyres got worn out -shoes got worn out -wear and tear in machinery
3.2.2. -Friction occurs whenever two moving surfaces are in contact. -Friction slows down and stops a moving object. -Friction produces heat.
3.3. Magnetic Force
3.3.1. -A magnet can attract objects made of iron and steel. -the magnet exerts a force called a magnetic force. -A magnet can also exert a force on other magnets. Example: Like poles of two magnets repel ( push ) Unlike poles of two magnets attract ( pull )