Updated date:

# Physics O Levels Formula Sheet

1) Speed

= distance / time

s = d / t (in symbol)

unit = km/h , m/s , cm/s

2) Acceleration

= change in velocity / time

a = v - u / t (v = final speed, u = Initial Speed, t = Time)

unit = m/s2

3) Average Speed

= total distance travelled / total time taken

s = d / t

unit = km/h, m/s, cm/s

4) Velocity

= displacement / time

v = dis / t

unit = m/s, km/h, cm/s

5) Force

= mass x acceleration

F = ma

unit = N (newton)

6) Weight

= mass x gravitational field strength

W = mg

unit = N (newton)

7) Density

= mass / volume

ρ = m / v

unit = g/cm3, kg/m3

8) Moment

= Force x perpendicular distance

m = F x d

unit = Nm (newton meter)

9) Principal Of Moment

sum of clockwise moment = sum of anticlockwise moment

F x d = F x d

10) Extension

x = L - l0

unit = mm , cm

11) Pressure

= Force / Area

p = F / A

unit = Pa (Pascal) , N/m2

12) Liquid Pressure

= density x gravity x height of the liquid

P = p g h

unit = Pa, N/m2

13) Pressure volume relationship of a gas

initial pressure x initial volume = final pressure x final volume

P1 V1 = P2 V2

14) Pressure transmission

initial force / initial area = final force / final area

F1 / A1 = F2 / A2

15) Kinetic Energy

= 1/2 x mass x (velocity)2

KE = 1/2 mv2

Unit = J (Joule)

16) Potential Energy

= mass x gravity x height

PE = mgh

unit = J

17) Work done

= Force x distance (travelled in the direction of force)

W = F x d

unit = J

18) Power

= work done or energy supplied/ time taken

p = W / t

unit = W (Watt) , KW (kilo watt)

19) Efficiency

= energy output / energy input x 100

Or

= power output / power input x 100

Unit = %

20) Heat Capacity

= thermal energy / change in temperature

C = E / Δ T

unit = J/0C

21) Specific heat capacity

= thermal energy / mass x change in temperature

c = E / m ΔT

unit = J/kg °C , J/g °C

22) Specific latent heat

= thermal energy / mass

l = E / m

unit = J/kg , J/g

23) Wave Equation

speed of wave = frequency x wavelength

v = f λ (λ is wavelength)

24) Frequency

= 1 oscillation / time taken

f = 1 / t

unit = Hz

25) Electrical Power

= Voltage x Current

Or

= (voltage)2 / Resistance

Or

= (current)2 x resistance

p = VI , p = V2/R, p = I2/R

unit = W (watt) , KW (kilo watt)

26) Refractive index

n= sin i / sin r (when going from rarer to denser medium)

Or

n= sin r / sin i (when going from denser to rarer medium)

Or

n = 1 / sin c (c is the critical angle)

27) Resistance

= Voltage / Current

R = V / I

unit = Ω (ohm)

28) Current

= charge / time

I = Q / t

unit = A (ampere) , mA

29) Electromotive force

= work done / charge

e.m.f.= E / Q

unit = V

30) Potential difference

= work done / charge

p.d = E / Q

unit = V

31) Resistance is series

R= R1 + R2 + R3

unit = Ω

32) Resistance in parallel

1/R = 1/R1 + 1/R2 + 1/R3 . . .

Or

R = R1 x R2 / R1 + R2

unit = Ω

33) Temperature

θ = Xθ - X0 / X100 - X0 x 100 (θ is the unknown temperature and X is the physical property of the thermometric substance)

34) Electrical energy

= voltage x current x time

Or

= power x time

E = VI , E = Pt

unit = J, KWh

35) Cost of electricity

= energy in KWh x cost per unit

36) Hook's Law

= F1 / x1 = F2 / x2 (F is the force and x is the extension)

• You can rearrange any of the equation according to the question. These are important formulas and other formulas can be made by changing the subject of the equation.