iGCSE Physics Formula sheet
Motion
Average speed (m/s) =
distance (m)
Time (s)
Average velocity (m/s) = displacement (m)
time (s)
(v = s /t)
Acceleration = change in velocity
time
Forces and pressure
(a = v-u )
t
Force (N) = mass (kg) x acceleration (m/s2)
(F = ma)
Force (N) = rate of change of momentum
(F = m v – mu )
T
Weight on Earth (N) = mass (kg) x 10 (m/s2)
(F = mg)
Momentum (kg m/s) = mass (kg) x velocity (m/s)
(p = mv)
Density (kg/m3)=
( = M / V)
mass (kg)
Volume (m3)
Hooke’s law: Force = constant x extension = kx
(F = kx)
Pressure (Pa) = force (N)
area (m2)
(P = F/A)
Pressure underwater = height (m) x density (kg/m3) x gravitational field strength (10m/s2)
(P = h x  x g)
Moment of a force (Nm) = Force (N) x perpendicular distance from pivot (m)
(moment = Fd)
Energy and work
Work (J) = Force (N) x distance (m)
(E = Fd)
Power (W) = work (J)
(P = E/t)
time (s)
Kinetic Energy (J) = ½ x mass (kg) x velocity2
(KE = 1/2mv2)
Gravitational potential energy (J) = mass (kg) x gravitational field strength (g) x height (m)
(GPE = mgh)
Efficiency (%) =
useful energy output (J) x100
total energy input (J)
Energy (J) = mass (kg) x specific heat capacity (J/kg oC) x change in temperature (oC)
Waves
Wave speed (m/s) = frequency (Hz) x wavelength (m)
(c = f)
Refractive index = speed of light in vacuum
speed of light in material
(n = v1 / v2)
Refractive index = 1 / sin (critical angle in degrees)
(n = 1 / sin c)
(n = sin i / sin r)
refractiveindex =
sini
sinr
Gas laws
Pressure x volume = constant (when a gas is it constant temperature)
(PV = constant)
For change in pressure:
Electricity
Current (A) = charge (C)
(I = Q/t)
Time (s)
Voltage (V) = Current (A) x Resistance ()
(V = IR)
Power (W) = Current (A) x Voltage (V)
(P = IV)
Energy transferred (J) = Current (I) x Voltage (V) x time (s)
(E = IVt)
Resistors in series:
Resistors in parallel:
Transformers:
Power in primary = Power in secondary
(IpVp = IsVs)
Radioactive decay