5.1 Temperature, Thermal Energy, and Heat

Why are there different colors on a thermal image?

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​Focus Question

​Heat

Specific Heat

​Temperature

Thermal Energy

You can use the words hot and cold to describe temperature. Something is hot when its temperature is high. When you heat water on a stove, its temperature increases.

​Temperature

the ability to cause change; equivalent to the ability to do work.

​Energy

​Thermal Energy

​​The thermal energy of an object is the sum of the kinetic energy and the potential energy of all the particles that make up that object. For example, as butter is warmed, the kinetic energy of its particles increase and the butter's thermal energy increases.

​Heat

• Heat is energy that is transferred between objects due to a temperature difference between those objects.

• Warmer objects always heat cooler objects, but the reverse never occurs. For example, a hot stove will heat a cold pot of water. However, a cold pot of water can never heat a stove.

The specific heat of a meterial is the amount of heat needed to raise the temperature of 1 kg of that material by 1°C. Scientists measure specific heat in joules per kilogram degree Celsius [J/(kg · °C)]

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​Specific Heat

​When thermal energy is added to water, some of the added thermal energy has to over-come some of the attraction between the molecules before those molecules can start moving faster.

​In metals, electons can move freely. When thermal energy is added, no string attractions need to be overcome before the electrons can start to move faster

• A scientist can calculate the specific heat of a material from the measurements that he or she takes from a calorimeter, such as the one shown below.

• To determine the specific heat of a material using a calorimeter, a scientist measures the mass of a sample of the material and the mass and initial temperature of the water in the calorimeter.

• The scientist then heats the sample, measures the sample's temperature, and places the sample in the water in the inner chamber of the calorimeter.

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Measuring Specific Heat