It's an isothermal change.

这是恒温的变化。

麻省理工公开课 - 热力学与动力学课程节选

PROFESSOR BAWENDI: So the question was, for an isothermal expansion, delta u does not change, therefore, The answer is that's true only for an ideal gas.

你的问题是，在等温过程中，内能是否，这只对理想气体成立。

麻省理工公开课 - 热力学与动力学课程节选

For isothermal expansion, that means that delta u does not change, but delta q is equal to delta w?

在等温过程中，是不是内能不变，Δq等于Δw？

麻省理工公开课 - 热力学与动力学课程节选

PROFESSOR BAWENDI: So, for an ideal gas, the isothermal is the easy one because the energy doesn't change.

对理想气体，等温过程最简单,因为能量不变。

麻省理工公开课 - 热力学与动力学课程节选

Therefore, if it's isothermal, the energy of the ideal gas doesn't change.

理想气体的，能量不变。

麻省理工公开课 - 热力学与动力学课程节选