87 Heat Energy-High

Heat Energy Written by Felicia Brown

Introduction Whether we stand next to a blazing bonfire, step barefoot across a sun-baked parking lot, or watch a pot of soup boil or an ice cube melt, we are experiencing the effects of heat energy. There are many kinds of energy in addition to heat energy. Sound energy and electrical energy are two kinds. Light energy and chemical energy are two others. But heat energy is one form of energy we experience every moment of our lives. We use it to warm our bodies, cook our food, heat our houses, dry our clothes, and run our cars. In this book, you will learn about heat energy. You'll learn how it is produced, used, and measured, as well as how it moves from place to place.

Sources of Heat Energy You know that heat is useful. But did you ever take time to think about all the sources of heat energy? One of the easiest ways to produce heat is to rub your hands together very fast. The rubbing of two objects together produces friction. Rubbing rough objects together usually produces more friction than rubbing smooth objects together. More friction produces more heat.

One of the most common sources of heat is fuel. When fuels such as coal, gasoline, and wood burn, they make heat energy. A forest of trees produces huge amounts of heat energy when it burns during a forest fire. Heat from burning gasoline makes cars and trucks run. Electricity is another source of heat energy. Electric furnaces heat our homes and schools. Toasters, irons, and hair dryers are just a few other things that use electricity to produce heat.

There are also natural sources of heat energy. For example, lightning is a natural form of heat (and light) energy. It produces tremendous amounts of heat, which makes air expand very fast. This expanding air causes thunder. And did you know that Earth has its own heat buried deep underground, called geothermal heat? It's so hot under Earth's crust that rocks melt. Sometimes the molten rock erupts on the surface from a volcano. In other places, the molten rock stays underground and heats water trapped there. The heated water later shoots out of the ground as a geyser.

Our most important source of heat is the Sun. Have you ever stepped from the shade into sunlight and felt warmer? You may think that heat travels from the Sun to Earth, but it doesn't. Sunlight is radiant energy. Radiant energy travels to Earth in waves of tiny particles. When sunlight hits your skin or other things on Earth, it gets absorbed. Then it turns into heat. Your microwave uses another kind of radiant energy to cook your food.