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. Measuring
3.1. Forces can be measured using force meters. Force meters are spring balances
3.2. Spring Balances (Force Meters): -Compression Spring Balances -Extension Spring Balances
4. A force can...
4.1. Change the shape or size of an object
4.2. Change the direction of a moving object
4.3. Start a stationery object
4.4. Stop a moving object
4.5. Change the speed of a moving object, by increasing its speed or slowing it down.
5. What is A Force?
5.1. A force is a push or a pull
5.2. Actions such as lifting, bending, twisting, stretching, squeezing, etc. involves pushes and pulls.
5.3. Forces are exerted only when one thing interacts with another.
6. Types of Forces
6.1. Gravitational Force
6.1.1. -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.
6.2. Frictional Force
6.2.1. 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
6.2.2. -Friction occurs whenever two moving surfaces are in contact. -Friction slows down and stops a moving object. -Friction produces heat.
6.3. Magnetic Force
6.3.1. -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 )