AQA GCSE Physics Paper 2

vectors

forces with magnitude and direction

scalars

forces with magnitude but no direction

contact forces

requires contact eg friction

non contact forces

doesnt require contact eg gravity

mass and weigth

directly proportional

weight

mass x gravitational field strength

gravitational field strength on earth

9.81

resultant force

the overal force acting on an object

if a resultant force moves and object

work is done

scale drawings

triangular drawings, finding the hypotenuse usually using pythagoras or trigonometry

object in equilibrium

when to forces acting on the object are balanced

extension

directly proportional to force

(spring) force

spring constant x extension

limit of proportionality/elasticity

when an elastic object gets stretched too much and it become plastic

moment of a force

force x perpendicular distance from pivot to the line of action of the force

levers

make it easier to do work and increase the distance form a pivot

gears

transmit rotational effects

pressure of an obeject

force ÷ area

pressure in fluids

height above point X density of fluid X gravitational field strength

pressure of a fluid

a force is exerted at right angles to any surface in contact with the fluid

a floating object

weight + upthrust

objects in water

experience upthrust

atmospheric pressure

decreases with height

an object will sink...

if it displaces a volume of water less than the objects weight

an object will float...

if it displaces a volume of water more or equal to the objects weight

distance

is scalar

displacement

is a vector

speed

how fast something is going

velocity

how fast youre going in a particular direction

distance travelled

speed x time

acceleration

change in velocity ÷ time

distance time graph

gradient = speed

velocity time graph

gradient = acceleration

drag increases...

as speed increases

friction

slows things down

objects falling through fluids (gas or liquid)

can reach a terminal velocity

newtons first law

objects with balanced forces acting on them will stay at rest, or in constant motion.

newtons second law

force + mass x acceleration

inertia

the tendency for motion to remain unchanged

newtons third law

when two objects interact the forces the exert on each other are equal and opposite

stopping distance

thinking distance + braking distance

thinking distance variants

speed, reaction times

reaction time inhibitants

drowsiness, alcohol/drug influences, concentration/distraction

braking distance variants

speed, weather, tread on wheels, brakes condition

braking

relies on the friction between tires and road

momentum

mass x velocity

total momentum laws in a closed system

total momentum before collision will be the same as the total momentum after collision

force (momentum)

change in momentum ÷ change in time

waves

transfer energy in the direction they are travelling

amplitude of a wave

height between undisturbed position and crest

wavelength

distance between crests or troughs

crests

top point

trough

bottom point

transverse waves

have sideways vibration eg electromagnetic waves

longitudinal waves

parallel vibrations eg sound

wave speed

frequency x wavelength

period of a wave

1/frequency

measuring sound

using an oscilloscope

angle of incidence in a reflection

= angle of reflection

specular reflection

uniform incoming rays reflect uniformly at 90 degrees off a shiny/smooth surface

diffuse reflection

uniform incoming rays reflect and scatter in all directions off a rough surface

refraction

waves changing direction at a boundary eg surface of water

the electromagnetic spectrum

radio waves, micro waves, infra-red radiation, visible light, ultraviolet, x-rays, gamma rays

radio waves

made by oscillating changes, has lowest frequency

uses of radio waves

carrying TV, radio and phone signals

uses of microwaves

communications - satellites TV an phone signals

cooking - ovens create microwaves that are absorbed by water and causes heat

infrared radiation

used to increase or monitor temperature

uses of infrared radiation

toasters, night vision

infrasound

sounds lower than the human hearing range (20Hz)

a suntan is created by...

ultraviolet radiation

used in medicine

x rays and gamma rays

uses of ultrasound

scanning unborn babies, navigation under water

ultrasound

sounds higher than the human hearing range (20,000Hz)

uses of x-rays

used in the detection of broken bones and internal cracks

uses of ultraviolet light

forgery detection, sunbeds

uses of gamma rays

killing bacteria, sterilising equipment

concave lens

causes light to diverge

convex lens

light rays meet after passing through lens

rules of refraction in lenses

incident ray parallel to the axis refracts through the lens and passes through the principal focus on the other side

an incident ray passing through the principal focus refracts through the lens and travels parallel to the axis

an incident ray travelling through the axis continues in that direction

distance from the convex lens

affects the image size

magnifying glasses

use convex lenses

visible light

made of a rage of colours

white

all colours

black

absence of colour

how colour is seen

an object absorbs all coloured light except the colour of the light that the object is which is then reflected into our eyes

colour filters

if a coloured object is covered by a colour filter that is a different colour then the object will appear black

leslie cube

investigates emission with different coloured and textured sides

every object emits and absorbs...

infrared radiation

radiation within the atmosphere and space

affects the earths temperature

compression in sound waves

a collection of sound particles in a sound wave

rarefaction in sound waves

sparser sound particles in a sound wave

how sound is heard

ear drum vibrates

how an ultrasound works

the transmitter/receiver transmits particles that hit the foetus (for example) and are then reflected back showing the size. or submarines do the same to find the bottom of the ocean, like echolocation

seismic waves

caused by earthquakes and explosions

p waves

primary longitudinal waves that travel through liquids

s waves

secondary transverse waves that cannot travel through liquids

the focus of an earthquake

where the fracture occured

the epicentre of an earthquake

the place on earth where the fracture is closest to

what is the combine point?

where 2 waves interact

permanent magnets

produce their own magnetic fields