IGCSE physics revision formualas 2023.

1. Average speed (ms^-1)

1. Average speed (ms^-1)

distance (m) / time (s) or v = d/t

2. Average velocity (ms^-1)

displacement (m) / time (s) or v = s

3. Period of a pendulum (s)

total time (s) / number of swings or T = t

4. Acceleration (ms^-2)

(final velocity (ms^-1) - initial velocity (ms^-1)) / time (s) or a = (v - u)/t

5. Weight (N)

mass (kg) x gravitational field strength (ms^-2) or F = mg

6. Force (N)

mass (kg) x acceleration (ms^-2) or F = ma

7. Density (kgm^-3)

mass (kg) / volume (m^3) or rho = M/V

8. Hooke’s law: Force (N)

constant (Nm^-1) x extension (m) or F = kx

9. Pressure (Pa)

force (N) / area (m^2) or P = F/A

10. Fluid Pressure (Pa)

density (kgm^-3) x gravitational field strength (ms^-2 or Nkg^-1) x height (m) or P = rho x g x h

11. Work (J)

force (N) x distance moved (m) or change in E = Fd

12. Power (W)

work (J) / time (s) or P = change in E/t

13. Kinetic Energy (J)

1/2 x mass (kg) x velocity^2 (ms^-2) or KE = 1/2mv^2

14. Gravitational potential energy (J)

mass (kg) x gravitational field strength (ms^-2 or Nkg^-1) x height (m) or GPE = mgh

15. Efficiency (%)

useful power output (W) x 100 / total power input (W) or Efficiency = Pout/Pin

16. Efficiency (%)

useful energy output (J) x 100 / total energy input (J) or Efficiency = Eout/Ein

17. Moment (Nm)

force (N) x perpendicular distance from pivot (m) or M = Fd

18. Sum of clockwise moments (Nm)

sum of anticlockwise moments (Nm) or F1d1 = F2d2

19. Momentum (kgms^-1)

mass (kg) x velocity (ms^-1) or p = mv

20. Force (N)

change in momentum (kgms^-1) / time (s) or F = change in p/t

21. Impulse (kgms^-1 or Ns)

change in momentum (kgms^-1) or Ft = change in p

22. Centripetal Force (N)

mass (kg) x velocity^2 (ms^-2) / radius (m) or F = mv^2/r

23. Orbital Period (s)

2 x pi x radius (m) / velocity (ms^-1) or T = 2(pi)r/v

1. Boyle’s Law for changes in gas pressure at constant temperature

P1V1 = P2V2 or PV = constant

2. Energy (J)

mass (kg) x specific heat capacity (Jkg^-1 x °C^-1) x temperature change (°C) or E = mc(change in)T

3. Thermal capacity (J°C^-1)

mass (kg) x specific heat capacity (Jkg^-1°C^-1) or C = mc

4. Energy transferred (J)

mass (kg) x specific latent heat (Jkg^-1) or E = ml

5. Expansion (m)

linear expansivity (°C^-1) x original length (m) x temperature rise (°C) or Expansion = alpha x l x (change in)T

1. Current (I)

charge (C) / time (s) or I = Q / t

2. Voltage (V)

energy transferred (J) / charge (C) or V = E / Q

3. Voltage (V)

current (I) x resistance (ohms) or V = IR

4. Power (W)

current (I) x voltage (V) or P = IV

5. Power (W)

current^2 (I) x resistance (ohms) or P = I^2 x R

6. Energy transferred (J)

current (I) x voltage (V) x time (s) or (change in)E = IVt

7. Energy transferred (J)

power (W) x time (s) or (change in)E = Pt

8. Resistors in series

Total Resistance (ohms) = sum of individual resistors (ohms) or RT = R1 + R2 + R3 + ... + Rn

9. Resistors in parallel

1 / total resistance (ohms) = sum of individual resistors (ohms) or 1 / Rtotal = 1 / R1 + 1 / R2 + 1 / R3 + ... + 1 / Rn

10. Resistance (ohms) Note: since wires have a circular cross-section area = pi x radius^2

resistivity (ohms m) x length (m) / area (m^2) or R = rho x l x / A

12. Transformers

voltage in the secondary coil (V) / voltage in primary coil (V) = turns on secondary coil /turns on primary coil or Vs = Vp / Ns = Np

13. Transformers

voltage in the primary coil (V) / voltage in the secondary coil (V) = current in the secondary coil (A) / current in the primary coil (A) or Vp = V/s / Is = Ip

Wave speed (ms^-1)

frequency (Hz) × wavelength (m) or c = f(lambda)

Frequency (Hz)

1 / Period (s) or F = 1 / T

Refractive index (n)

sine of the angle of incidence

Refractive index (n)

speed of light in vacuum / speed of light in material or n = cv / cm

Refractive index (n)

1 / sine of the critical angle or n = 1 / sinc

RadioActive alpha decay

Radioactive beta decay

Radioactive gamma decay

Energy (j)

Mass defect (kg) x speed of light² (ms^-1) or E=mc²

The earth speed (v)

•  2 x (pi) x r / T

Light year (m)

9.5 × 10¹⁵m

Hubbles constant (Ho)

v / D or 2.2 × 10^–18 per second

Age of the universe

d / v = 1 /Ho