MadSci Network: Physics |
Hi Chun,
actually both things are exactly the same! You have two different
possibilities for motion - either all atoms are moving concerted (i.e. in
the same direction) or in different directions. If they move concerted -
the item moves as a whole (a baloon or so) but if they are moving in
different directions, then the item as a whole doesn't move at all. That
kind of motion is exactly what we call "temperature"!
But you are asking why they start to vibrate - in physics there exists a
principle called the "equipartition principle". It states that all
translational (motion) rotational and vibrational degrees of freedom have
the same amount of energy - you can't have just vibrational energy.
If you are really interested, have a look at this web page or search a chemistry page.
Bye,
Andreas
Try the links in the MadSci Library for more information on Physics.