work done

• energy - is the potential to do work
• 4 main energy stores

  1. chemical - food, fuel, burning wood, glucose in muscles
  2. thermal - heating
  3. kinetic - anything that moves has kinetic energy
  4. gravitational potential energy - eg, skier at the stop of a hill
• thermal energy equation

  change in energy - mass x specific heat capacity x change in temperature --> specific heat capacity equation
• kinetic energy equation

  kinetic energy = 0.5 x mass x velocity2
• gravitation energy equation


  g p e = m x g x h
• other energy stores

  1. elastic potential energy - strecthed elastic band
  2. nuclear energy - nuclear reactor, hydrogen in the sun
  3. electrostatic potenial energy - between 2 opposite charges that are held apart
  4. magnetic potential energy - 2 opposite poled held apart.
• elastic potential energy equation

  energy - 0.5 x spring constant x extension 2
• nuclear energy equation

  Energy = mass x speed of light 2
• types of energy transfers

  1. mechanical - physical work
  2. heating
  3. electrical
  4. radiation
• conservation of energy


  total energy before = total energy after
• power = work done / time
• one watt is equivalent to 1 joule per second