Chapter 1: Force and Pressure

what is force

when we push or pull an object, we exert a force

effects of force

change the direction of moving objects

change the speed of moving objects

change the state of rest or motion of a body

cause objects to turn

change the size and shape of objects

types of forces

contact forces

non-contact forces

frictional force

magnetic force

gravitational force

frictional force acts when 2 surfaces are in contact with each other

force of attraction or repulsion between two magnets

force of attraction between two bodies

friction acts in the opposite direction to motion

how to reduce friction

apply lubricants like grease or oil to the surfaces in contact

preventing or reducing contact between the two objects

attach ball bearings to the surfaces in contact

having a smooth body reduces water and air resistance

having a streamlined body shape

can act at a distance

Weight of a body is the gravitational force acting on it

weight

mass

amount of matter in a body

gravitational force acting on a body

SI unit: kilogram(kg)

SI unit: newton(N)

formula

W=mxg

pressure

force acting per unit area

formula

P=F/A

the smaller the area, the greater the pressure. the greater the area, the smaller the pressure

SI unit: pascal(Pa)

knife's cutting edge is very thin, allowing the knife to cut objects easily

caterpillar tracks on tanks increase the area of the tank touching the ground, reducing pressure on the ground and allowing the tank not to get stuck in mud