Principle of Conservation of Energy Flashcards
what does the principle of conservation of energy state
- energy cannot be created or destroyed
- but only be transferred from one form to another
what are the main energy transfers that occur in a thermal power station when generating electricity
- the chemical energy in the fuel is converted into the internal energy stores of the compressed steam
- which is then converted into electrical energy
what illustrations are mainly used to represent energy transfers
sankey diagrams
what does the width of the input of the arrow represent
the total energy of the system
how would the energy transfers occurring be represented on a sankey diagram
with outgoing arrows pointing downwards and straight ahead from the body of the input energy
how are the amounts of energy in each conversion represented
- by the width of the arrows
- the thicker the arrow is the more energy that is going down that route
what is the important thing about sankey diagrams which proves the conservation of energy
- the sum of the widths of outputs (outgoing arrows) equals the width of the input
- this shows that the input energy is equal to the output energy
- so energy has been conserved
what two types of output arrows would you have
- you would have the arrows drooping downwards
- representing wasted or not useful energy
- whereas you would have an arrow pointing forwards
- indicating the useful energy
what is the ability to transfer the input energy to desired energy called
the efficiency of the system
how do calculate efficiency
efficiency = (useful energy / total energy) x 100