What Causes Rain?
What Causes Rain? You know that rain falls from clouds. Water is constantly evaporated from the earth’s surface by the warmth of the sun. The invisible water...
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How Do Jet Engines Work?
How Do Jet Engines Work? You can make a simple jet engine by filling a balloon with air and letting it go. Jet engines work on the principle that every action has an...
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Is Breathing Cold Air Dangerous?
Breathing cold air isn’t dangerous. Your body has special mechanisms in place to make sure that all the air that reaches your lungs is plenty warm and full of...
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What Is Gravity?
When you toss a ball into the air, it comes down because it is pulled to earth by gravity. Gravity is a force that pulls all things on the earth toward the...
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What Makes a Fire Smoke?
What Makes a Fire Smoke? The smoke that rises from a chimney or a bonfire is made chiefly of gases that are produced when the fuel burns. Most of the gases in wood...
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