What causes rotation?

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Chemistry can tell me <b>HOW</b> liquids are produced but not <b>WHY</b> liquids are produced.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">True. But physics supplies the WHY. Molecules vibrate.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">If their vibrations are small enough, the nuclear forces dominate and hold all molecules together and in place. The result is a solid.

If their vibrations have speeds that exceed escape speed, the molecules are no longer captives, but can flow. They remain in contact only because of viscous forces.

If the vibration speeds are great enough to overcome viscous forces, individual molecules fly off into space. If they are in a container or bound by some force such as gravity, they form a medium of discrete particles we call a "gas".

If the vibration speeds exceed even the escape speeds of the forces containing them, they form a plasma.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

the thing is though how does your explaination, explain the liquidification of hydrogen at extremely low temps. since the vibrations would be practicly zero. same with oxygen, oxygen also liquifies at very low temps.(not as low hydrogen though) and then when both get together they liquify at room temperature!!

in my view it is the plasma that is condensed in the atom itself(the plasma is already there)i'm thinking that the liquid state is caused by the density of the plasma because of the low temps. yet this still does not explain why the liquid state can still form at room temps. its as if there is, perhaps, some sort of catalist at work here.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by north</i>
<br />how does your explanation explain the liquidification of hydrogen at extremely low temps. since the vibrations would be practicly zero.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Molecular vibration is not something separate from temperature. It <i>is</i> temperature. The stronger the molecular vibrations, the hotter those molecules are. If the vibrations cease. the temperature is absolute zero.

BTW, this is not "my" explanation, but standard physics as I understand it. -|Tom|-

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by EBTX</i>
<br />Two objects moving relative to one another have, say, "x" angular momentum and "y" linear momentum (using the backdrop of stars as a reference frame). Neither X nor Y changes no matter what they do in this two-body situation. The quantities x and y never convert into one another.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Suppose we kick a ball. Its path appears linear for a short time until gravity redirects its linear momentum. The upward component of linear momentum is gradually diminished, becomes zero, then starts to increase downward. The path of the ball is a curved arc. The same is true if any force acts of a particle with linear momentum. That linear momentum can be redirected. It does not change character, but it does change direction.

Note that the definition of "force" is "the time rate of change of momentum". Both force and momentum are vectors, meaning that they have both magnitude and direction. The "change" produced by a force can occur in either magnitude or direction.

If the force is strong and continuous, as for a ball on a string being twirled by a central observer, the ball's path is a closed circle. The ball still has linear momentum, but it is being continually redirected. In general, when the force acting on the ball or particle is the force of cohesion in a material body, the particle's linear momentum is being continually redirected. When linear momentum is being continually redirected by a central force, we call it "angular momentum". There is no "conversion". Angular momentum is simply linear momentum maintained with respect to a center rather than with respect to the distant stars.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">if such a conversion were possible, a spinning object could convert some of its angular momentum into linear momentum and "take off to the stars" without throwing something out in the opposite direction.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">A body can spin so fast that the centrifugal force on a surface particle is greater than the force holding the particle attached to the spinning body. In that case, the particle does "take off to the stars" because it still has linear momentum before and after it leaves the spinning body. -|Tom|-