Sorry I wasnt able to dumb this down for people that dont know science regarding air pressure...but here Is my knowledge In how psi In Inflated objects need to be looked at regarding this Inflatefate with the Patriots....Im smarter than I will let on here but I just cant hold back on this issue any longer seeing the most ignorant peoples comments about what they think they know about psi being affected and I doubt they passed 5th grade Science. So welcome to Brians Science class 101 on P.S.I. There has been a fair amount of bad comment about whether temperature can account for the observed football deflation in the AFC Championship game. Many of the calculations just use the pressure measured by a gauge on the ball, but this is a mistake. You need to account for the fact that the measurement is a gauge measurement, not an absolute measurement of pressure. This is the argument: If the balls were initially inflated to 12.5 psi (the minimum) in a locker room at 75 F, then the pressure inside the balls at 45 F (like at halftime on the field) would be about 11 psi — already down by 2 psi from the nominal 13 psi inflation pressure. The calculation is trivial, uses the Ideal Gas Law, the fact that the pressure measurements are gauge measurements (relative to the base atmospheric pressure, (I used 14.7 psi for the base atmospheric pressure)), not absolute pressure measurements, and assume the football volume doesnt change. Additionally, each pressure measurement takes a little air out of the ball, and multiple measurements can also significantly reduce the pressure. Cyclists understand this. Given the multiple pressure measurements that were made, plus natural leakage due to rough play, plus temperature differences, all this could very easily result in more than a 2 psi pressure drop, measured at or near field conditions. Here are the numbers: 75 F = 297 Kelvin (Need to use absolute temperatures) 45 F = 280.4 Kelvin 280.4/297 = the absolute pressure ratio = (X +14.7)/(12.5 + 14.7) Where X is the gauge measurement of the ball pressure at the field temperature, 45 F. X = 10.98 psi. 2 psi less than the nominal 13 psi. Just from temperature differences. Differences with the balls used by the Colts could easily be explained by different preparation procedures, or even longer waits between preparation and the referee check. Especially if the the Colts QB, Luck, likes higher initial ball pressure — as has been reported. There have also been reports that the balls weighed less. Ridiculous. Air doesnt weigh much. You would have to weigh the balls to a couple of tenths of a percentage, and you couldnt do that by just holding the balls. Now that I finally got all the Science out of the way that was eating at me inside since this bullshit over 2 psi started.......it didnt matter....the Patriots were the better team on the field.
Posted on: Mon, 26 Jan 2015 23:49:37 +0000
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