# Temperature is base on the average kinetic motion of all atoms

1. Sep 21, 2010

### ntc2019

Sorry for this silly question , I am still high school student . I know that temperature is base on the average kinetic motion of all atoms. But kinetic motion is not absolute so in what case should we use this formula: v= $$\sqrt{\frac{3RT}{\mu}}$$ . Should it be the velocity in respect to the center of mass? In that case , two objects have the same average velocity may have different temperature like that when we open a box fill with vacuum and close it fast enough when the temperature inside that box is different from outside because the air only go in the box in one way . Thank you for reading my question .