![]() |
If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#17
|
|||
|
|||
![]()
On Feb 10, 5:53*pm, Mxsmanic wrote:
writes: Since there is no infinite volume, what would be the point? The atmosphere of the Earth is an infinite volume, and in fact it demonstrates rather well that the combined laws don't apply in that case. *Pressure is largely uncorrelated with temperature, for example. Half knowledge can be a dangerous thing in the wrong hands. The fact that you cannot correlate pressure and temperature in the atmosphere does not mean the gas laws do not apply. It just means that the number of molecules in a given volume of the atmophere , ie density varies with height with time, with winds etc. At any point in the atmosphere ( or in space) the density of any block of space over which the temperature and pressure can be considered to be constant, can be calculated accurately using the gas equation density =PM/RT You see the fact that the volume of the atmophere or of space is infinite is quite irrelvant because nobody wants to know what the average density of the whole atmophere is ( which of course will approach zero depending on your definition of where the atmsophere actually ends) . But a pilot might want to know what the density is in a particular layer of air where the temperature and pressure are reasonably constant, say at an airport for example that he is going to take off from and wants to know whether his aircrafts performance will be sufficient to takeoff and clear a bunch of trees at the end of the runway. And in the case of the space example, you quoted a pressure of 1e-11 Pa, if the temperature is 3 deg C then again the density will be able to be calculated perfectly well for that part of space for which that temp and pressure apply, the fact that the temperature and pressure in some other part of infinite space is different,is irrelevant , the gas laws apply everywhere ( with appropriate modifications for non ideal behaviour at very high temps and pressures but I wouldnt worry about those if I were you, try to understand the basics first) Terry PPL Downunder . |
Thread Tools | |
Display Modes | |
|
|
![]() |
||||
Thread | Thread Starter | Forum | Replies | Last Post |
yrb-49-taxi.jpg | [email protected] | Aviation Photos | 2 | September 25th 07 09:50 PM |
Hanoi Taxi | john smith | Piloting | 0 | April 27th 06 03:48 AM |
License To Taxi? | SteveT | Piloting | 29 | October 16th 05 04:57 PM |
Leaning for taxi | Jim Rosinski | Piloting | 28 | September 12th 04 03:53 AM |
taxi in reverse? | [email protected] | Owning | 20 | February 21st 04 12:26 AM |