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Welcome to our Physics lesson on Internal Energy, this is the first lesson of our suite of physics lessons covering the topic of Molar Specific Heats and Degrees of Freedom, you can find links to the other lessons within this tutorial and access additional physics learning resources below this lesson.
For simplicity, let's consider a monoatomic gas whose atoms move only in a translational way. Also, let's assume the internal energy of this gas is only due to the sum of translational KE of all atoms, neglecting the presence of any chemical form of energy in the system.
As explained in the previous tutorial, the translational kinetic energy of a single atom is given by the formula
If we have a gas of n moles, it contains n × NA atoms. Therefore, the internal energy of gas (which corresponds to the average kinetic energy of all its atoms), is
Given that the Boltzmann constant k is given by
we obtain for the internal energy of gas U:
Since n and R are constants, we conclude that:
The internal energy of an ideal gas is a function of temperature only. In other words, it depends only on the temperature of gas.
You have reached the end of Physics lesson 13.8.1 Internal Energy. There are 4 lessons in this physics tutorial covering Molar Specific Heats and Degrees of Freedom, you can access all the lessons from this tutorial below.
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