FORCES AND PRESSURE

1. Magnetic force is the force of attraction produced by magnets on objects made of iron, steel and other magnetic materials. Like poles of magnets face each other they repel. Likewise, when unlike poles of magnets face each other they attract.

2. Gravitational force is a force that pulls objects down towards Earth. The force of it pulling down on an object is called weight.

3. Friction is a force produced when 2 moving objects are in contact. It is useful for example it is needed for walking. It also can be a nuisance as it opposes and slows down movement.They can be reduced when using smooth surfaces, ball bearings, etc.

4. There are 3 important forces around us. (magnetic, frictional and gravitational forces)

5. The SI unit of force is newton (N) which is named after Sir Isaac Newton.

6. Force is a push or a pull. We usually exert it when we do actions like stretching, twisting,etc.

7. We cannot see force but the effects. For example, force can change the speed of the moving object, change the shape or size of an object, start an object or stop a moving object and change the direction of a moving object.

8. Force is measured using 2 types of force meters: extension and compression spring balances. When force acts on them they extend or compress appropriately.

9. Pressure is the force exerted per unit area. It increases when (a) force increases, or (b) area increases. The calculation of pressure is force divided by area. The SI unit is pascal (Pa) where 1 Pa = 1 N/ cubic metre