Energy transfers
Energy moves from one thing to another – follow the energy chain.
Energy on the move
Energy can transfer from one object to another. Hold an ice cube: heat energy transfers from your warm hand to the ice, and it melts. Heat always moves from hotter things to colder things.
Heat transfers from a cup of hot tea to your hands and to the air, so the tea slowly cools down until it is the same temperature as the room.
Energy chains
We can show energy transfers as an energy chain. Sun → wet washing: the Sun’s energy transfers to the clothes and the water evaporates. Each arrow means “transfers energy to”.
You can make an energy chain for anything that uses energy: food → your muscles → a pedalled rickshaw → movement.
Heating water with the Sun
A solar water heater has dark panels on the roof. Light and heat from the Sun transfer to the panels, then to the water in the pipes. Sun → panels → water → hot shower!
Black surfaces absorb more of the Sun’s energy than white ones, so solar heater pipes and panels are painted black.
Investigating heat transfer
Put a metal spoon in hot water. Soon the handle feels warm. Heat energy is conducted along the metal. The hotter the water, the faster the handle warms up.
Metals conduct heat well; wood and plastic do not. That is why cooking spoons often have wooden or plastic handles.
What I learnt
- I know that energy can transfer from one object to another.
- I can draw an energy chain.