Principle of Conservation of Energy

Question 1

what does the principle of conservation of energy state

Answer 1

• energy cannot be created or destroyed

- but only be transferred from one form to another

Question 2

what are the main energy transfers that occur in a thermal power station when generating electricity

Answer 2

• the chemical energy in the fuel is converted into the internal energy stores of the compressed steam
• which is then converted into electrical energy

Question 3

what illustrations are mainly used to represent energy transfers

Answer 3

sankey diagrams

Question 4

what does the width of the input of the arrow represent

Answer 4

the total energy of the system

Question 5

how would the energy transfers occurring be represented on a sankey diagram

Answer 5

with outgoing arrows pointing downwards and straight ahead from the body of the input energy

Question 6

how are the amounts of energy in each conversion represented

Answer 6

• by the width of the arrows

- the thicker the arrow is the more energy that is going down that route

Question 7

what is the important thing about sankey diagrams which proves the conservation of energy

Answer 7

• 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

Question 8

what two types of output arrows would you have

Answer 8

• 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

Question 9

what is the ability to transfer the input energy to desired energy called

Answer 9

the efficiency of the system

Question 10

how do calculate efficiency

Answer 10

efficiency = (useful energy / total energy) x 100