Conservation of energy

• Law of conservation of energy?

  Energy cannot be created or destroyed, only transferred or transformed from one form to another.
• How can efficiency be increased?

  Reduce waste output (e.g. lubrication to reduce friction, insulation to reduce thermal loss). Recycle waste output (use waste thermal energy as input)
• Energy dissipation

  Energy not transferred to useful energy stores
• Units of energy?

  Joule (J)
• Units of power

  Watt (W)
• Improve efficiency of radiator?

  Install reflective foil to reflect heat (get more useful thermal energy)
• Improve efficiency of boiling water in pan

  Add lid to stop heat escaping
• Energy transfers

  mechanical. electrical. heating. radiation
• How does thermal transfer by radiation work?

  radiation involves transfer of heat via infra red waves. The sun provides heat to the earth due to radiation.
• What is maximum energy efficiency?

  1 (if percentages 100%)
• Equation for percentage energy efficiency

  useful energy output / total energy input
• Energy efficiency in percentage equation


  $\dfrac{USEFUL\hspace{2mm}OUTPUT\hspace{2mm}energy}{TOTAL\hspace{2mm}INPUT\hspace{2mm}energy} \hspace{1mm} \times 100 \hspace{5mm}$
• Energy efficiency equation


  $\dfrac{USEFUL\hspace{2mm}OUTPUT\hspace{2mm}energy}{TOTAL\hspace{2mm}INPUT\hspace{2mm}energy}$