for instance, for the thermos with the coffee in if you place the boundary in the inside wall of the glass or the outside wall of the glass and the inside of the thermos, that makes a difference; different heat capacity, etcetera.

比如说，对于装咖啡的热水瓶来说,你把边界设置在瓶胆的内壁上,或者设置在瓶胆外壁上,或设在热水瓶里面，情况都是不一样的;,有不同的热容等等。

麻省理工公开课 - 热力学与动力学课程节选