ENERGY

Energy Transfer by Heat Processes – Rate of Thermal Energy Transfer & Heating and Insulating Buildings

Energy Transfer by Heat Processes – Rate of Thermal Energy Transfer & Heating and Insulating Buildings

The shape and dimensions of a body will affect the rate at which heat is transferred. Also, the difference in temperature between a body and its surroundings will also affect the rate at which heat is transferred: the bigger the difference (for example, if a body is hot and the surroundings cold) the faster the rate.

Little animals, like mice, have a big surface area compared to volume. This means that they lose their heat at a fast rate to their surroundings. To cope with this they need to eat a lot.

Large animals, like elephants, have a small surface area compared to volume. This means that the rate at which they lose heat is very slow. To prevent themselves from overheating they have big ears which increases their surface area and helps them to lose heat at a faster rate.

The rate of thermal energy transfer also depends on:

  • – the material of an object
  • – what the object’s in contact with.

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Heating and insulating buildings

When designing a building it’s important to minimise heat lose as much as possible. This is why insulating materials are used. An insulator is measured in U-values: the smaller the U-value the better the material is as a heat insulator. A U-value of 1 W/(m2