Thermal motion txhais tau hais tias cov khoom yog tsim los ntawm cov molecules, atoms thiab ions, thiab cov molecules ntawm tag nrho cov khoom nyob rau hauv tas li txav, thiab lawv nyob rau hauv tsis xwm yeem txav. Lub thermal txav ntawm molecules muaj feem xyuam rau qhov kub ntawm cov khoom. Qhov siab dua qhov kub ntawm cov khoom, qhov nrawm nrawm ntawm nws cov molecules.
