Potpourri starting May 17, 2010

[robinson46176]

OK! verbiage How did your 'mental and physical model' end up with 4 ft³ and .25 ft³ as the volumes for the inflated and uninflated tire tire respectively?verbiage
verbiage
Methinks you are 'evading' the question!:rolleyes: verbiage verbiage verbiage verbiage verbiage verbiageverbiage verbiage verbiage verbiage verbiage...

verbage?

I don't know all of the formulas and I have never even met mister Boyle but I do understand the relationship between a 10 pound rabbit and a 1,000 horse both cooked and uncooked...
I wonder if they used an open kettle or a pressure cooker.
.
I also have a good mental general grasp of ratios and relationships. I guess that is why I almost never use plans and often build stuff from a picture or just memory. I may fly by the seat of my pants a lot but I seldom crash.

[JPG]

Now your question is clear. 4 cu ft came from an internet search. .25 cu ft. came from an estimate I made by taking my boats deflated inner tube, pressing all the air to one area, twisting the tube to block off the air and then continuing to twist, tightening it to a point were it was pressurized. Then, I squished it some more in a box with a board to further pressurize it to a point where I estimated it was at about 30psi by comparing the feel of then tube to the feel of my mountain bike tire which is at 30 psi. I then looked at this volume and determined that it was about 1/4 ft. cu. Crude method but any estimate is better than no estimate. My 98% vs. Ed Boyle's 93% wasn't too shabby 'ay?

Evading the question??? I wanted you to clarify your question since in the past, answering those vague questions leads to typing a response that was no where near what your were looking for in your head. Figured I'd save myself typing for nothing.

Translation: PIOOMA!:rolleyes:

[a1gutterman]

Thank you gentlemen! Going by your explanations, I see that there is somewhat more nitrogen in a tire filled with 100% nitrogen then I thought there was. Even so, I think that if my tire is low, rather then drive to Costco for 100% nitrogen, I will be adding regular air with 78% nitrogen.

[robinson46176]

Thank you gentlemen! Going by your explanations, I see that there is somewhat more nitrogen in a tire filled with 100% nitrogen then I thought there was. Even so, I think that if my tire is low, rather then drive to Costco for 100% nitrogen, I will be adding regular air with 78% nitrogen.

That is the product I use...
Only American air of course.

[mickyd]

Translation: PIOOMA!:rolleyes:

But 4 cu ft really DID come from an internet search....

[JPG]

But 4 cu ft really DID come from an internet search....

And that was the ONLY detail I 'believed'!:D

[dachsieslave]

I know I am a little late to the party and it really doesn't matter, but I just couldn't let it go.

Reible, I am hate to tell you but you misused Boyles Law. It simply says for a given amount of gas at constant temperature a change in volume gives an inverse change of pressure.

What we need here is the ideal gas law (well to keep it simple)

PV = nRT

P = pressure
V = volume
n = amount of gas in moles
R = ideal gas constant (8.314)
T = temperature in Kelvin ( we will use standard temp of 293)

solving for n gives us
n = PV/RT

So our empty "tire" of 4 has n= (14.7*4)/(8.314*293)= .024 moles

Our full tire has n = (32*4)/(8.314*293) = .053 moles
Now the empty tire has air with 78% Nitrogen so: .78*.024 = .019 moles
the amount of Nitrogen we added is .053-.024 = .029 moles
Total % of Nitrogen in tire is (.029+.019)/.053 = 90.05%

Now this assumes no change in volume, which we know is not the case. So the actual % will be higher due to the increase in volume, now we could figure that out with a little more complexity (and I would have to break out my old books for that formula).

I sure hope I haven't bored you all too much

[JPG]

. . .
I sure hope I haven't bored you all too much

Not in the least!:)