Formulae

• weight = mass x gravitational field strength

  W = m g
• work done = force x distance

  W = F s
• force applied to a spring = spring constant x extension

  F = k e
• distance travelled = speed x time

  s = v t
• acceleration = change in velocity / time taken

  a = Δv / t
• resultant force = mass x acceleration

  F = m a
• wave speed = frequency x wavelength

  v = f λ
• density = mass / volume

  ρ = m / V
• momentum of a force = force x distance (normal to direction of force)

  M = F d
• pressure = force normal to a surface / area of that service

  p = F / A
• momentum = mass x velocity

  p = m v
• kinetic energy = 0.5 x mass x (speed)$^2$

  Ek = 1/2m v$^2$
• gravitational potential energy = mass x gravitational field strength x height

  Ep = m g h
• power = energy transferred / time

  P = E / t
• power = work done / time

  P = W / t
• efficiency = useful output energy transfer / total input energy transfer
• efficiency = useful power output / total power input
• charge flow = current x time

  Q = I t
• potential difference = current x resistance

  V = I R
• power = potential difference x current

  P = V I
• power = (current)$^2$ x resistance

  P = I$^2$ R
• energy transferred = power x time

  E = P t
• energy transferred = charge flow x potential difference

  E = Q V