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0625 Physics formula sheet Cheat Sheet (DRAFT) by

0625 IGCSE physics formulas updates every 2 weeks with a new chapter

This is a draft cheat sheet. It is a work in progress and is not finished yet.

Energy

kE = 1/2mv2
F = ∆p/∆t
∆GPE = mg∆h
W = Fd = ∆E
W = Fd
(%) efficiency = (useful energy output) (total energy input) × 100%
(%) efficiency = (useful power output) (total power input) × 100%
P = W / t
P = ∆E/ t
p = F / A
∆p = ρg∆h
T (in K) = θ (in °C) + 273
pV = constant
c = ∆E / m∆θ

Forces

∆p = ρg∆h (liquid pressure)
Pressure = force / area
W = m x g
kE = 1/2mv2
a = v-u / t
R.F = F.F - B.F
R.F or F = m x a
R.F or F = m x a = m x (v-u/t) = mv - mu /t = change in momentum/t
F = ∆ momentum or P/∆t
impulse = R.F or F x ∆t
impulse = change in momentum/ change in time
m1u1+ m2u2 = m1v1+ m2v2 (conse­rvation of momentum)
m1u1 + m2u2 = (m1+m2) x V (when objects stick together)

Thermal physics

kE = 1/2mv2
F = ∆p/∆t
p is inversely propor­tional to V
W = Fd = ∆E
p1v1 = p2v2
c = ∆ E m∆θ
specific heat capacity = change in thermal energy­/mass x change in temper­ature
P = ∆E/ t
p = F / A
∆p = ρg∆h
T (in K) = θ (in °C) + 273
pV = constant
c = ∆E / m∆θ
 

waves

where n is the refractive index, V is speed of light
n = sin(i)­/sin(r)
n = 1/ sin(c)
n2/n1 = V1/V2 = sin(i)­/sin(r)
n ( in air ) = 1
V (in air) = 3x 10^8
v = f λ
State the approx­imate range of freque­ncies audible to humans as 20Hz to 20000Hz
speed of sound in air is approx­imately 330–350m/ s
Define ultrasound as sound with a frequency higher than 20kHz

Electrical quantities

potential difference is the work done by a unit charge passing through a component, measured between two points in volts (V)
electr­omotive force (e.m.f.) is the electrical work done by a source in moving a unit charge around a complete circuit measured in volts (V)
kilowa­tt-hour (kWh) 1000 watts per one hour
1 kWh = 3.6 x 10^6 J
resist­ance, the opposition of a component to the flow of electric current through it measured in ohms (Ω)
charge is measured in coulombs, where one coloumb is he charge on 6.24 x 10^18 electrons
R1/R2 = V1/V2
R total = R1 x R2 = R1 + R2 or produc­t/sum
resistance is directly propor­tional to length (b) resistance is inversely propor­tional to cross-­sec­tional area
the p.d. across an arrang­ement of parallel resist­ances is the same as the p.d. across one branch in the arrang­ement of the parallel resist­ances
the sum of the currents entering a junction in a parallel circuit is equal to the sum of the currents that leave the junction
the total p.d. across the components in a series circuit is equal to the sum of the individual p.d.s across each component
 

Space Physics

v = 2π r/T
where r is the average radius of the orbit and T is the orbital period; recall and use this equation
one light-year is equal to 9.5 × 1015m
astron­omical distances can be measured in light-­years, where one light-year is the distance travelled in (the vacuum of) space by light in one year
the diameter of the Milky Way is approx­imately 100000 light-­years
H0 = v d
Define the Hubble constant H0 as the ratio of the speed at which the galaxy is moving away from the Earth to its distance from the Earth
d/v = 1/H0
represents an estimate for the age of the Universe
speed of light in a vacuum is 3 × 10^8
d = v/t

Electr­icity

I = Q / t
emf = W/Q
pd = W/Q
R = V/I
P = IV
E = IVt
R1/R2 = V1/V2
R total = R1 x R2 = R1 + R2 or produc­t/sum

Motion

Density = Mass/ Volume
(constant) S = distance / time
a = v-u / t
D (while accele­rating) = v+u x t
D = area under the graph
W = m x g
R.F/ F = m x a
R.F = F.F - B.F
Moment = force x perpen­dicular distance from the pivot
Pressure = force / area
(Liquid) pressure = Density x g x height
X = L new - L original
F = k/x , where k is the spring constant