9-1 Physics/Conservation of energy

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Heat Flow[edit | edit source]

Each year we spend millions of pounds heating our houses, but much of this heat escapes through our windows and roofs. We can use our understanding of temperature and heat flow to help us reduce our energy usage and save us money.

Temperature[edit | edit source]

Temperature is a measurement of how hot something is using a chosen scale usually degrees Celsius, °C (but sometimes Fahrenheit, °F).

Heat is a measurement of energy on an absolute scale, always joules, J.

If there is a difference in temperature between an object and its surroundings then this results in the flow of heat energy from the hotter region to the cooler region.

If an object's temperature rises it is taking in heat energy. For example, if you take a can of cola out of the fridge it will soon warm up to room temperature because the can takes in heat energy from the air in the room.

If an object's temperature falls it is giving out heat energy. For example, a hot cup of tea will soon cool down. If you hold it in your hands you will feel the heat energy flowing from the cup into your hands.