Re: Poor People's Greatest Hits
necoandjeff wrote:
> Brett Robson wrote:
>
>
>>>The kinetic energy (vibration) of the molecules in the air, which
>>>vibrate from heat and strike the underside of the airfoil. Because
>>>the air molecules are "stretched out" from the curved flow of the
>>>air across the top of the air foil, the total kinetic energy of
>>>molecules striking that side isn't enough to counterbalance the
>>>force under the airfoil. But this is all quite different from saying
>>>the sail is "pushed" by the wind which is blowing (roughly) at a
>>>right angle to the sail. We both basically understand what is going
>>>on here from the perspective of physics. You were simply wrong to
>>>say that I was technically wrong by saying that the wind doesn't
>>>push the sail, unless for some reason you aren't making a
>>>distinction between "wind" and "air."
>>>
>>
>>You've got several concepts confused here. Kinetic energy is
>>movement, not vibration (that's not quite correct but let's drop
>>that hot potato). A vibrating particle at rest has no kinetic
>>energy (sort of). In a fluid (gas, liquid and plasma) heat is not
>>molecules vibrating, heat is molecules moving, literally having
>>kinetic energy. You may be thinking of Browian motion which is
>>the movement of macro objects impacted by molecules.
>
>
> You're right. My use of the word "vibrating" was wrong. I was thinking of
> the molecules literally flying to and fro from their kinetic energy and it
> came out as vibrating. Of course I don't mean to convey that the molecules
> sit there and vibrate like a guitar string and are otherwise stationary.
> Delete the parenthetical and replace the second "vibrate" with "move" and
> what I said is otherwise fine.
I was interested to learn that something that is vibrating has no
kinetic energy. The physics of resonance must have undergone a
revolution. I wonder what makes a spring work now?
I was also interested to learn that a particle can be at rest.
- Kevin
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