Physics Formulae

Remember, c = 3 X 10⁸ms^-1 and speed of sound = 340ms^-1

Power(W) = Current(A) X Voltage(V)

P = IV
Current(A) = Charge(C) / time(s)

I = Q / t
Potential Difference(V) = Current(A) X Resistance (Ohms)

V = IR
Potential Difference(V) = Energy(J) / Charge(C)

V = J / Q
Resistance (Ohms) = 1 / Conductance (Siemens)

R = 1 / G
Conductance (Siemens) = 1 / Resistance (Ohms)

G = 1 / R
Total Resistance [in series](Ohms) = Sum of resistors (Ohms)

R_T = r₁ + r₂ + r₃
Total Conductance [in series](Siemens) = Inverse sum of conductance(Siemens)

G_T = 1 / G₁ + 1 / G₂ + 1 / G₃
Total Resistance [in parallel](Ohms) = Inverse sum of resistors (Ohms)

R_T = 1 / r₁ + 1 / r₂ + 1 / r₃
Total Conductance [in parallel](Siemens) = Sum of Conductance (Siemens)

G_T = G₁ + G₂ + G₃
%Efficiency = useful output / input X 100

[Efficiency of power station]

Kinetic Energy(J) = 1/2 X Mass(kg) X Velocity²(m/s)

KE = 1/2mv²
Gravitational Potential Energy(J) = Mass(kg) X Gravitational Field Stregth(N/kg) X Vertical Height(m)

GPE = mgh [g = 9.81N/KG on Earth]
Voltage across secondary(V) / Voltage across primary(V) = number of turns in secondary / number of turns in primary

Vs / Vp = Ns / Np [Transformers]
Work(J) = Force(N) X Distance moved in direction of force(m)

W = Fd
Power(W or J/s) = Work done(J) / time taken(s)

P = W / t

Force (N) = Gravitational Constant X Big Mass (Kg) X Small Mass (Kg) / Distance² (m)

F = GMm / r²
Speed(m/s) = distance(m) / time(s)

V = d / t
Acceleration(m/s/s) = Change in velocity(m/s) / time taken(s)

a = ∆ V / t
Force(N) = Mass(kg) X Acceleration(m/s/s)

F = ma
Moment(Nm) = Force(N) X Perpendicular distance from pivot(m)

M = Fd
Weight(N) = mass(kg) X acceleration of free fall(m/s²)

w = mg [g = 10m/s² on Earth]
Weight(N) = mass(kg) X Gravitational Field Strength(N/kg)

w = mg [g = 10N/kg on Earth]
Pressure(N/m²) = Force(N) X Area(m²)

p = f / a
Density = mass / volume

d = m / v

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