Equations

• Kinetic energy

  kinetic energy = 0.5 × mass × (velocity)^2
• Elastic potential energy

  elastic potential energy = 0.5 × spring constant × (extension)^2
• Gravitational potential energy

  gravitational potential energy = mass × gravitational field strength × height
• Change in thermal energy

  change in thermal energy = mass × specific heat capacity × temperature change
• Power (energy)

  power = energy transferred/ time
• Power (work)

  power = work done/ time
• Efficiency (energy)

  efficiency = useful output energy transfer/ total input energy transfer
• Efficiency (power)

  efficiency = useful power output/ total power input
• Charge flow

  charge flow = current x time
• Potential difference

  potential difference = current x resistance
• Power (P.D)

  power = potential difference x current
• Power (resistance)

  power = = (current)^2 × resistance
• Energy transferred (Power)

  energy transferred = power × time
• Energy transferred (charge)

  energy transferred = charge flow × potential difference
• Density

  density = mass/volume
• Thermal energy change for a change of state

  thermal energy for a change of state = mass × specific latent heat
• For gases (constant)

  pressure x volume = constant
• Weight

  weight = mass × gravitational field strength
• Work done

  work done = force × distance (along the line of action of the force)
• Force

  force = spring constant × extension
• Moment of a force

  moment of a force = force × distance (normal to direction of force)
• Pressure

  pressure = force normal to a surface/ area of that surface

  
  

  (force/area)
• Pressure due to a column of liquid

  pressure due to a column of liquid = height of column × density of liquid × gravitational field strength
• Distance travelled

  distance travelled = speed × time
• Acceleration

  acceleration = change in velocity/ time taken
• (final velocity)^2- (initial velocity)^2

  (final velocity)^2 - (initial velocity)^2 = 2 × acceleration × distance
• Resultant force

  resultant force = mass × acceleration
• Momentum

  momentum = mass x velocity
• Force (momentum)

  force = change in momentum/ time taken
• Period

  period = 1/frequency
• Wave speed

  wave speed = frequency x wavelength
• Magnification

  magnification = image height/ object height
• Force on a conductor (at right angles to a magnetic field) carrying a current

  force on a conductor (at right angles to a magnetic field) carrying a current = magnetic flux density × current × length
• Potential difference across primary coil/ potential difference across secondary coil

  potential difference across primary coil/ potential difference across secondary coil = number of turns in primary coil/ number of turns in secondary coil
• Potential difference across primary coil x current in primary coil

  potential difference across primary coil × current in primary coil = potential difference across secondary coil × current in secondary coil