ΔU = Q – W (Work done by the system): Here, W is positive when the system does work on its surroundings (like a gas expanding), and negative when work is done on the system (like compressing a gas).
ΔU = Q + W (Work done on the system): W is positive when work is done on the system (compressing the gas), and negative when the system does work on its surroundings (gas expanding).
The above equations are the mathematical expressions of the first law of thermodynamics.
- ΔU (Change in Internal Energy): This represents the change in the total energy contained within the system. A positive ΔU means the internal energy has increased, while a negative ΔU means it has decreased.
- Q (Heat Added to the System): Heat is a form of energy transfer. If heat is added to the system (like heating a pot of water), Q is positive. If heat is removed from the system (like cooling the pot), Q is negative.
- W (Work Done by the System): Work is another way to transfer energy. If the system does work on its surroundings (like a gas expanding and pushing a piston), W is positive. If work is done on the system (like compressing the gas), W is negative.
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Our internal energy calculator makes it easy to explore these relationships! Just input the values for any two of the variables (ΔU, Q, or W), and the calculator will determine the third. This helps you understand how heat, work, and internal energy are all interconnected. Experiment with different values and see how the energy of a system changes!
