Electricity

P = V x I. power = voltage x current.

V = I x R. voltage = current x resistance.

Q = I x t. charge = current x time.

E = V x Q. energy = voltage x charge.

E = V x I x t. energy = voltage x current x time.

Transformer Equation

Total cost = number of units x cost per unit.


Energy

Efficiency (%) = (useful energy out ÷ total energy in) x 100.

GPE = mgh. GPE = mass x gravity x height.

KE = ½mv2. Kinetic Energy = 0·5 x mass x velocity2.

W = F x d. work done = force x distance.

W = E. work done = energy transferred.

P = E ÷ t. power = energy ÷ time.

E = c x m x θ. energy = specific heat capacity x mass x change in temperature.


Forces and Motion

s = d ÷ t. speed = distance ÷ time.

a = (v-u) ÷ t. acceleration = change in velocity ÷ time.

F = m x a. Force = mass x acceleration.

w = m x g. weight = mass x gravity.

p = m x v. momentum = mass x velocity.

(mv - mu) = F x t. change in momentum = Force x time.

d = m � v. density = mass ÷ volume.

p = F ÷ a. pressure = force ÷ area.

m = F x d. moment = force x perpendicular distance from pivot.


Waves

v = f x λ. velocity = frequency x wavelength.