Boats, hot air balloons, helium balloons: all of these things defy gravity. Gravity is pulling down on them, but they don't fall all the way to the ground. If you had a helium balloon on the moon, it would not rise: gravity would prevail and pull the balloon to the ground. That's what gravity does. …

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Why is it that the cheesy part of a pizza can burn your mouth, but the crust doesn't? They both came out of the same oven, at the same temperature, but it seems like the cheese has more "heat" (actually internal energy ) stored inside of it. When you put it in your mouth, it …

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So, the first law is , where means the change in internal energy, is the heat, and is the work done. This is true whenever the thing we're paying attention to isn't losing or gaining particles, which we'll consider later. Let's check our understanding. Consider an air canister, like those used to blow dust out …

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Energy and Temperature In the previous post I detailed the First Law of thermodynamics, which says that if something happens to a system or object, the thing called the internal energy of the object undergoes a change Don't pay attention to the actual equation. Just realize that the internal energy is increased by adding heat, …

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When you are cold, one of the things you do instinctively is rub your hands together, or rub your arms with your hands. This warms them up by way of friction. That is, we have heated something up by motion. Caveman knew how to warm up his hands this way. He knew that rubbing made …

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