86 Heat Energy-Mid

Heat Energy Written by Felicia Brown

Introduction Have you ever stood next to a campfire? Have you ever watched soup boil or ice melt? If so, you have felt or seen heat energy at work! There are many kinds of energy, such as sound energy and electrical energy. But it is heat energy that we see and feel the most. We use it to cook our food, heat our houses, and run our cars. In this book, you will learn where heat energy comes from, how it is used, how it moves, and more.

Sources of Heat Energy Have you ever wondered about all the ways we get heat energy? One easy way to make heat is with friction, or the rubbing together of two objects. Rub your hands together very fast. Can you feel the heat? Rough objects often make more friction than smooth objects, and more friction makes more heat!

Burning fuel is another way we make heat. When fuels such as coal, gasoline, and wood burn, they make heat energy. Heat from burning gasoline is used to make cars and trucks run. Electricity is another way we get heat energy. Electric furnaces heat homes and schools. Toasters, irons, and hair dryers are just a few other things that use electricity to make heat.

Heat energy comes from natural sources, too. Lightning is a natural source of heat that makes air spread out very fast, causing 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 comes out at the surface through a volcano. In other places, the molten rock comes close to the surface but doesn't come out. This melted, underground rock can heat water trapped in the ground. The water later shoots out of the ground as a geyser.

The Sun is our most important source of energy. Have you ever stepped from the shade into sunlight and felt warmer? You may think that heat comes straight 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, it changes to heat. Your microwave oven uses another kind of radiant energy to cook your food.