Forces and Pressure

1. Pressure is the force exerted on a surface per unit square.

2. Pressure increases when surface area decrease, or force increases. In another word, it depends on two factors which are area and force.

2.1. E.g. For the same force exerted, the smaller the surface area in contact, the higher the pressure on the object.

3. 3 types of forces

3.1. Fictional force

3.1.1. A force produced when two surfaces are in contact, it opposes and slows down movements which causes excessive heat produced and wore off objects. However, it is useful and we cannot live without it, e.g. it is needed in walking. We can reduce it by using lubricants, streamlining, smooth surfaces and ball bearing.

3.2. Gravitational force

3.2.1. A force which pulls objects towards the center of the Earth .

3.3. Magnetic force

3.3.1. A force which results in attraction and repulsion with magnets and most metals.

4. Effects of forces

4.1. it changes the speed and direction of a moving object.

4.2. It changes the size and shape of a object.

4.3. Make thing move or stop

5. Ways to measure force

5.1. We use two types of spring balances which are extension and spring balances.( NOTE: we do not use beam balance as it is only for measuring mass)

5.2. EXTRA(Sec 3 formula): F=M*A If we know the mass and the acceleration which is the moving speed of the object, we will be able to find out the force.

6. S1 unit for force is newton and its symbol is (N).

7. Force is a push or a pull.