Heat is a form of energy. Temperature tells us how hot or cold something is. They are linked but not the same: temperature is a measure, while heat is the energy that flows.
Measuring temperature
We measure temperature with a thermometer. The unit is degrees Celsius (°C). The Sun is the biggest natural source of heat for the Earth. Fire and hot stoves are other sources of heat.
Key idea
Heat always flows from a hotter object to a cooler object, until both are the same temperature.
What heat does
When most things are heated, they expand (get a little bigger). When they cool, they shrink back. This is why a warm drink left in a cool room slowly loses heat and cools down. Heat can travel through solids, liquids and gases. We feel warm when heat moves into our body and cool when heat moves away from it. A thermometer helps us measure these changes exactly instead of just guessing.
Remember
- Heat = a form of energy.
- Temperature is measured in °C with a thermometer.
- Heat flows hot → cold.