1. What is a force?
1.1. - a push or a pull
1.2. - exerted when one thing interacts with each other
1.3. Everything needs a force
1.4. We can't see a force, only the effects of it
2. Effects of a force..
2.1. A stationary object moves
2.1.1. New node
2.2. Change the direction of an object
2.3. Make a moving stop
2.4. chang the shape of an object
2.4.1. New node
2.5. change the speed of a moving object
3. Important Forces..
3.1. Gravitational force
3.1.1. -Also known as gravity -A person’s weight is actually the amount of gravitational force acting on him -Depends on mass -A force pulling us ‘downwards’ towards the center of the earth
3.2. Magnetic force
3.2.1. -Attraction or Repulsion between two magnets -Like poles repel, Unlike poles attract -Dependent on the distance between the two magnets - Also dependent on how strong each magnet is
3.3. Frictional force
3.3.1. -The force exerted by a surface as an object moves across it -Opposes the motion of a moving object (the other direction) -Dependent on the texture of both surfaces. -Also dependent on the amount of contact force pushing the two surfaces together -Air resistance and water resistance are forms of friction too
4. What is Pressure?
4.1. - the force acting per unit area. - increases when the force increases or the area decreases
4.2. Pressure = Force/Area
4.3. SI unit: N/m2 or Pascal
5. Examples of pressure questions..
5.1. 1 pin vs a board of pins and a balloon.
5.1.1. 1 PIN: balloon will burst.
5.1.2. contact area of 1 pin is smaller thus the pressure exerted is higher and the balloon will burst
5.1.3. A BOARD OF PINS: balloon will not burst
5.1.4. contact area between the balloon and pins is large thus force is exerted over a bigger area and the pressure is lower. Hence the balloon will not burst.
5.2. Football shoes
5.2.1. they have spikes below the sole to increase pressure exerted on the ground as all the spikes in total has lesser surface area compared to the whole area of the shoe sole. This allows the shoe to have a better grip and prevent the football player from falling.