The First Law of Thermodynamics is all about energy conservation. It states that energy cannot be created or destroyed, only transformed from one form to another. In simpler terms, the change in internal energy ($\Delta U$) of a system equals the net heat transfer ($Q$) into the system minus the net work ($W$) done by the system. Mathematically, this is expressed as: $\Delta U = Q - W$. Understanding this relationship is key to solving thermodynamics problems!
When solving problems, pay close attention to the sign conventions. Heat added to the system is positive, while heat leaving the system is negative. Work done by the system is positive, while work done on the system is negative.
Match the terms with their definitions:
| Term | Definition |
|---|---|
| 1. Internal Energy | A. Energy transferred due to temperature difference |
| 2. Heat | B. Energy of a system due to molecular motion and interactions |
| 3. Work | C. Energy transferred when a force causes displacement |
| 4. System | D. Part of the universe we are studying |
| 5. Surroundings | E. Everything outside the system |
Match the correct letters to the numbers!
The First Law of Thermodynamics states that the change in __________ energy of a system is equal to the __________ added to the system minus the __________ done by the system. This law is a statement of the principle of __________ of energy.
Imagine you have a sealed container with a fixed volume. If you add heat to this container, how does the internal energy of the gas inside change, and why? Explain in terms of the First Law of Thermodynamics.
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