1. Force
1.1. Definition
1.1.1. The capacity to do work or cause physical change, either a pull or a push.
1.1.2. It is a pull or a push.
1.2. SI Unit
1.2.1. Newton (N)
1.3. Effects of forces
1.3.1. change size and shape of object
1.3.2. move a stationary object
1.3.3. stop a moving object
1.3.4. change the direction
1.3.5. change the speed
1.4. Instruments to measure
1.4.1. spring balance
1.4.2. compression balance
1.5. Types of Forces
1.5.1. Frictional Force
1.5.1.1. A force that holds the object so that it will not move when it is being pulled or pushed.
1.5.1.2. Occurs when two moving surfaces are in contact
1.5.1.3. Effects of friction: slow down/ stop moving
1.5.1.4. Useful effects of friction: enable us to walk; light match stick
1.5.1.5. Negative effects of friction: wear and tear; produce heat and thus decreases the efficiency of machine
1.5.1.6. Ways to reduce friction: add lubricants such as oil,water, and other things such as ball bearings, smoothen the surfaces, streamlining. There is also lesser friction between two smooth surfaces than between two rough surfaces.
1.5.1.7. However, without friction, no one would be able to walk without slipping or even crawl around the floor. Almost nothing would be possible to carry out.
1.5.1.8. Therefore, frictional force is very important and is necessary for daily life.
1.5.2. Gravitational Force
1.5.2.1. Gravitational force is the force that pulls every living and non-living things towards the center of the earth OR a force that causes objects to be attracted to the Earth.
1.5.2.2. Examples: A coconut falling from a tree; a ball being thrown up will come down
1.5.2.3. To find out the weight of an object, the formula is Mass x Gravitational Strength
1.5.2.4. If on earth, the gravitational strength is 10, then the gravitational strength on moon is 1.6
1.5.2.5. Another word for Gravitational strength is weight as weight is the amount of gravity an object while mass is the amount of matter in an object.
1.5.3. Magnetic Force
1.5.3.1. The pull or push between two magnetic or one magnetic and one non-magnetic object OR a force exerted by a magnet in another magnet or on a magnetic material (iron, steel, cobalt, nickel)
1.5.3.2. There are many examples of magnetic force which can be taken from activities in our daily lives, for example the fridge.
1.5.3.3. Uses of magnetic force: door of fridge, EZ link card, junkyard, magnetic door catch, maglev train.
1.6. Formula
1.6.1. Pressure x Area
1.6.2. Mass x Acceleration
2. Pressure
2.1. Definition
2.1.1. The force acting on an area (per unit area).
2.1.2. Force per unit area applied in a direction perpendicular to the surface of an object.
2.1.3. Amount of force exerted per unit area
2.2. Symbol
2.2.1. p
2.3. High pressure
2.3.1. Decrease the surface area
2.3.2. Increase the force
2.3.3. Higher pressure will allow us to cut easily (they have smaller surface area) example: high heels, sharp knife.
2.4. Low pressure
2.4.1. Increase the surface area
2.4.2. Decrease force
2.4.3. Examples: skiing, camels' feet, army tank wheels/excavator
2.5. Formula
2.5.1. force : area
2.6. Unit
2.6.1. Pascal (Pa)
2.6.2. 1 Pa = 1N/sq metre