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Why work from expansion is the area under the curve of a PV-diagram. Why heat is not a state function and internal energy is a state function. Created by Sal Khan.

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Physics on Khan Academy: Physics is the study of the basic principles that govern the physical world around us. We'll start by looking at motion itself. Then, we'll learn about forces, momentum, energy, and other concepts in lots of different physical situations. To get the most out of physics, you'll need a solid understanding of algebra and a basic understanding of trigonometry.

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