1. How can we measure a force?
1.1. Forces are measured with force-meters. Spring balances are force-meters. -Extension spring balances -Compression spring balances
1.1.1. 1) In a compression spring balance, the spring is compressed when a force acts on it. 2) In a compression spring balance, the spring is compressed when a force acts on it.
2. What are the effects of forces?
2.1. A force can: Change the speed of a moving object Change the shape or size of an object Start an object moving or stop a moving object. Change the direction of a moving object
3. What is a force?
3.1. A force is a push or pull. Whenever we push or pull something, we are said to exert a force.
3.1.1. Lifting/ bending/ stretching/twisting/ squeezing involves pushes and pulls
4. What is pressure?
4.1. pressure is the force exerted per unit area.
5. How can we decrease pressure?
5.1. To reduce pressure, increase the area of the object to exert lesser pressure.
5.1.1. for example, a camel has large feet so the pressure exerted will be reduced and the camel will not sink into the sand.
6. How to calculate pressure?
6.1. To calculate pressure we use the formula : force/Area
6.1.1. The unit of pressure is N/m2 also known as pascal. Pascal is the SI unit for pressure. For example a hippopotamus weighs 40000N it stands on one foot on the ground what is the pressure? 40000N = 40/cm2 1000cm2
7. How can we increase pressure?
7.1. to increase pressure you reduce the area of the object to exert more pressure.
7.1.1. for example, a sharp knife will exert more pressure than a blunt knife.
8. Units for pressure
8.1. SI unit: N/m2 or Pascal (Pa) Other units: N/cm2
9. Units of forces
9.1. SI unit: Newton Symbol: N Named after English scientist Sir Isaac Newton
10. Different type of forces
10.1. Frictional force
10.1.1. Magnetic force
10.1.1.1. Gravitational force
11. Effects of the different forces
11.1. Frictional force: Also called friction Occurs when two moving surfaces are in contact Effects: Slows down and/or stops a moving object Produces heat
11.1.1. Magnetic force:Force exerted by a magnet on a magnetic material (e.g. iron and steel) or another magnet. Forces between magnets: Like poles repel: Magnets push away from one another Unlike poles attract: Magnets pull towards each other
11.1.1.1. Gravitational foce: Also called gravity Exists between any two objects This is the force that causes all objects to be attracted to the Earth.