If you want to determine how hot or how cold something is, you use a thermometer and check the temperature. You are actually measuring the kinetic energy of that object. Kinetic energy is energy of motion. A thermometer measures the average temperature of the molecules moving around it.

In Canada, we use the Celsius scale to measure the temperature of objects. In the United States, the Fahrenheit scale is more common. When you watch an American television station, sometimes you will see their daytime high temperatures as 86° F. This is warm but not as warm as you might think. In Canada, using the Celsius scale, this temperature is 30° C, which is a nice summer day! 

Sometimes the words temperature and heat are used to mean the same thing. Scientifically, these two terms mean different things. In this activity, you will learn how temperature and heat are different.

Temperature is the measure of kinetic energy. Heat is energy, thermal energy. Heat, or thermal energy, is the total amount of energy (both potential and kinetic) that molecules have in an object. Because heat is energy, it makes sense that the colder the substance, the less energy it has — and the warmer it is, the more energy it has.

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When heat moves into a substance, one of two things happen:

 1. the temperature rises — heat speeds up the molecules

    2. the substance can change state — solid to liquid, liquid to gas, solid to gas, gas to solid, gas to liquid, or liquid to solid

When a substance changes state, the temperature may or may not change. For example, water absorbs heat and changes from ice to water, but the temperature does not change.

This table summarizes state changes by the movement of heat.