physics mochs

speed equation

distance / time

acceleration equation

v-u / t

vetor quantity

has magnitude and direction e.g. velocity

scalar quantity

has only magnitude e.g. speed

unbalanced force eqution

f = m x a

gravitational field strength equation

weight / mass

stopping distance equation

thinking distance + braking distance

terminal velocity

Initially when falling, air resistance is low as speed is low. As speed increases so does air resistance. terminal velocity is when air resistance = speed.

power current and voltage relationship

p = I x V

energy transferred

E = I x V x t or E = Q x V

voltage equation

I x R

current definition

rate of flow of charge

charge equation

I x t

voltage definition

the energy transferred per unit charge

explain how inkjet printer work

tiny droplets of ink are forced out of a charged nozzle which makes them charged

the droplets are deflected as they pass two metal plates with voltage.

each droplet hits a different lace on the paper

how does a photocopier work

the image plate is positively charged

whiter bits you are going to make lighter puts light onto the paper which makes the charge leak away

the black powder is attracted to the positive plate

the paper is heated so the powder sticks

longitudinal waves

are where the vibrations area parallel to the direction of travel

transverse

are where the vibrations are perpendicular to the wave travel

amplitude

the maximum displacement of a wave

wavefront

an imaginary surface representing points on a wave that are in the same points of their cycle

frequency

the number of waves passing a point each second

wavelength

the distance of one peak to the next

period of a wave

the amount of time is takes for a complete wave to occur

wave speed equation

v = frequency x wavelength

v = f x λ

frequency equation

1 / t

reflection

when waves bounce off an even surface

refraction

when waves slow or speed up at a boundary between two materials

law of reflection

angle of incidence = angle of reflection

snells law (refractive index)

n = sin i / sin r

critical angle

when light is refracted along a boundary (r=90)

relationship between c and refractive index

sin c = 1/n

principal of energy

energy cannot be created or detroyed

efficiency equation

efficiency = (useful energy output) / (total energy output) x 100

thermal radiation

IR radiation consisting of electromagnetic waves

thermal conduction

the process where vibrating particles transfer energy from their kinetic energy store to the kinetic energy stores of neighbouring particles

thermal convection

where more energetic particles move from the hotter region to the cooler region and transfer energy as they do

conduction investigation

attach beads to a metal rod using wax

heat end of rod with no beads

record time for each bead to fall

convection investigation

place purple potassium permanganate crystals in cold water

heat and trace path of dissolution

refraction index investigation

place a clear block of paper and trace

place light source at angle

draw line of incidence and emergence

draw 90 line at angle of incidence

measure i and r

work done equation

force x distance moves

power equation (work)

power = work done / time taken

energy in kinetic energy store

½ x mass x speed²

thermal radiation invesigation

fill a Leslie cube with boiling water

measure IR coming from each surface

energy in gravitational potential energy store

mass x height x gravitational field strength

density equation

p = m / v

pressure equation

p = F / A

pressure difference equation

pressure difference = height x density x gravitational field strength

specific heat capacity equation

change in thermal energy = mass x specific heat capacity x change in temp

absolute zero

-273*C

pV constant

P₁V₁ = P₂V₂

p/T constant

P₁/T₁ = P₂/T₂

alpha beta and gamma rays definition

ionising radiations emitted from unstable nuclei in a random process

what is an alpha particle made of

2 protons snd 2 neutrons

what is a beta particle made of

an electron which was emitted when a neutron became a proton and electron

what is a gamma ray made of

electromagnetic waves

half life definition

the time it takes for a radioactive material to loose half of its radioactivity

orbital speed equation

(πr x orbital radius) / time

red shift equation

change in wavelength = velocity of galaxy

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reference wavelength = speed of light