Science across the curriculum.0:01
Exercise 1, page 152.0:05
Heating things up Temperature.0:10
Everyone understands temperature.0:22
We all can tell the difference between a sunny summer day and and an icy winter day.0:25
We realize when our tea is the right temperature to drink or when it will burn our tongue.0:31
Yet temperature is hard to define.0:37
A simple way to define temperature is to say that it is the number that you read on a thermometer.0:44
But what is the thermometer measuring?0:50
A more complicated answer is that a thermometer measures the average kinetic energy of a substance or an environment.0:53
In other words, it is measuring how fast the molecules that make up the substance are moving.1:01
A higher temperature means the molecules are moving more quickly.1:07
But isn't heat the same as temperature?1:13
Actually, heat is energy.1:18
It is measured in joules.1:21
When we feel that something is hot or cold, we feel the transfer of energy from a hot object to a colder object.1:24
This transfer of energy from hot to cold goes on all the time.1:32
This is why a cup of tea sitting on a table cools and why the ice in a glass of water melts.1:37
Heat versus Temperature.1:45
Although heat and temperature are not the same, they are related.1:49
If you add energy to a substance in the form of heat, the temperature of the substance usually goes up.1:53
But sometimes the state of the substance changes.2:00
For example, ice melts and water boils.2:04
We can see the difference between heat and temperature if we think of a pot of water on the cooker.2:08
If you heat a little bit of water, it boils quickly.2:15
But if you heat a full pot of water, it takes longer to boil.2:19
Both pots of water boil at the same temperature, but the full pot requires a lot more heat to reach that temperature.2:24
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