Energy Transfers
Science: KS3, topic 3.1.2
Energy Transfers
Energy can be transferred from its store via its pathway. All energy transfers follow the conservation of energy. Energy transfers can be shown as Sankey diagrams.
Conservation of energy
- The conservation of energy states:
- Energy cannot be made or destroyed.
- Energy is just transferred from one form to another.
Starting and ending energy
- The starting amount of energy is the same as the ending amount of energy.
- The energy has just changed form during the transfer.
Energy transfers
- Energy is transferred from its store via a pathway to another store.
- No energy is lost or gained during the transfer.
Useful and wasted energy
- Energy can be transferred into a useful energy store.
- Energy can also be transferred into a wasted energy store.
- Wasted energy is mostly transferred to the surroundings as thermal energy.
Sankey diagrams
- We can use Sankey diagrams to represent energy transfers in a system.
- Sankey diagrams show an input store and an output store.
- An arrow shows the pathway.
Energy and totals
- A thicker arrow block shows more energy transferred.
- The input store must equal the total output stores.
Test yourself on Energy Transfers
What is the law of conservation of energy?
In a Sankey diagram, what must the input store always equal?
A Sankey diagram shows two output arrows. Arrow A is thicker than Arrow B. Which statement is true about the energy they transfer?
A toy car slows down and stops because of friction with the floor. According to the conservation of energy, what happens to the kinetic energy it loses?