Unit 1 - Heat

This unit explains the principles of heat and temperature, and includes simple experiments which compare the insulating abilities of a variety of materials.  It includes background reading which introduces the concepts tested in;

Activity 1 Temperature worksheet
Activity 2 Keeping Heat In – an investigation
Activity 2 datasheet
Activity 3 Keeping Heat Out – an investigation

Background – An Introduction to heat and temperature

What is heat?
Heat is a form of energy. When something is heated, its molecules are given more energy and so they move around a bit more. The molecules knock off each other, moving further apart which generally makes the substance expand. Heat is measured in Joules (J) or kilojoules (kJ).

What is temperature?
Temperature and heat are not the same. Temperature tells us what level of heat is in something. Temperature is measured in degrees. For this unit, we will use the Celsius scale (°C), so we will talk about degrees Celsius. Fixed points on this scale are the freezing point of water, 0°C and the boiling point of water, 100°C. Normal body temperature is around 37°C.

What is insulation?
When it’s cold outside we wear heavier clothes and more of them. At night when we sleep, we cover up with a blanket. On hotwater tanks, many homes have lagging jackets. In these situations, clothes, blankets and lagging jackets provide insulation, helping keep heat trapped for longer. Insulators are materials which don’t let heat pass through very easily. It is difficult for heat to pass through insulators, or insulation materials. Having good insulation in our homes means less heat loss so it takes less energy to heat rooms and water.

What is heat transfer?
Heat moves from an area of high temperature to an area of low temperature, until both areas are the same temperature. For example, if you pour warm water over ice-cubes, heat flows from the water to the ice. The ice melts, and the water is cooler than before. What has happened is that the water lost heat and the ice gained heat until both mixed and were the same temperature. Heat can be transferred in three ways; conduction, convection and radiation.