Equations

• weight = mass × gravitational field strength g

  W = m g
• work done = force × distance along the line of action of the force

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

  F = k e
• moment of a force = force × distance normal to direction of force

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

  p = F / A
• distance travelled = speed × time

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

  a = Δ v / t
• resultant force = mass × acceleration

  F = m a
• momentum = mass × velocity

  p = m v
• kinetic energy = 0.5 × mass × (speed)2

  Ek = 1/2mv
• gravitational potential energy = mass × gravitational field strength (g) × 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 = total power output / total power input
• wave speed = frequency × wavelength

  v = f λ
• charge flow = current × time

  Q = I t
• potential difference = current × resistance

  V = I R
• power = potential difference × current

  P = V I
• power = (current)2 × resistance

  P = I2 R
• energy transferred = power × time

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

  E = Q V
• density = mass / volume

  ρ = m/V