Physics - forces

contact vs non-contact forces

contact - objects need to touch in order to experience a force

non - objects do not need to touch

6 examples of contact forces

friction

normal contact

upthrust

drag

tension

thrust

3 examples of non-contact forces

gravitational force

electrostatic force

magnetic force

friction

fa force which opposes the motion of an object

Newton (N)

The force needed to accelerate 1kg of mass by 1m/s²

situation with friction

a car driving will have friction on its wheels

situation with drag

planes flying have air resistance, a type of drag

situation with electrostatic

hand on a van der Graaff causes your hair to frizz and stand

situation with tension

an apple hanging from a tree

resultant force

resultant force is the sum of all forces, causing an object to accelerate or decelerate. If there no resultant force the object then it is stationary or moving at a constant velocity

2 ways to reduce friction

• add a lubricant

• smooth the surfaces

• extra - remove some of the masses

scalar

a quantity that only includes magnitude e.g. mass

vector

a quantity that includes magnitude and direction e.g. weight

weight

The force experienced by an object with mass when placed in a gravitational field

2 examples of temporary change in shape

• stretching a rubber band

• compressing a spring

2 examples of a permanent change in shape

• squashing a metal can

• burning paper

Hookes law

the force applied on an object is proportional to the extension

force equation

force = spring constant x extension

hookes law on a graph

it is shown by a straight line passing through the origin, therefore showing the force isn’t directly proportional

why place masses on the block

• increased friction

• increases pressure

why keep the masses constant

ensures a fair test

prefix of mega

10⁶

prefix of kilo

10³

prefix of centi

10^-2

prefix of milli

10^-3

prefix of micro

10^-6

equation of weight

weight ( N) = mass (Kg) x GFS ( N/M )

what is mass in terms of pull

the pull the object on earth

what is weight in terms of pull

the pull of the earth on the object

GFS is always equal to Mass

when solving the gfs is always of the other object ( the force its being pulled by )

Newtons law 1

an object at rest will remain at rest unless an external force acts upon it

Newtons law 2

force is equal to the objects mass x its acceleration

Newtons laws 3

whenever 2 objects interact, the forces they exert on each other are equal, in opposite directions and of the same ‘type‘

rules of newtons 3rd law

• forces always come in pairs

• act on different objects

• act in opposite directions

• are equal in magnitude

• are of the same ‘type‘

support force

compression = a restorative force

normal reaction force

it is the restoritive force that brings objects back to their original shape

compression

all solids have a giant lattice structure, when you apply a force the object slightly deforms before restoring back to its brought back to its original shape