tom.kordis
Practice Squad Player
- Joined
- Feb 4, 2015
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Well it's ambiguous whether "2 pounds under" means "2 pounds under nominal" or "2 pounds under minimum." If it's the latter, we still might need to find half a pound someplace. The fact that the one ball was apparently lower than the others supports some air having been let out (quite possibly unintentionally) during gauging.
True. Everything about news reports is - AT BEST - ambiguous.
These are the things that we can know for sure from that report:
- The guy that filed it is pretty clueless about measurements. No one who is really competent would have said "2 pounds" instead of "2 psi".
- The guy is sloppy, by virtue of not saying "below WHAT". (nominal or minimum)
So my approach is to (mostly) ignore the reporting, and stick with the science/engineering.
What I DO know about footballs (not just theory, but experimentation too) is the following:
- Any ball, EVERY ball, filled to 12.5 psig @ 75°F, and then exposed to 50°F air & 47°F water (1 minute water dunk, dry off, 9 minute cold air) for 70 minutes will record an internal pressure of about 11.0 psig.
- The only temperature that plays any role in determining the pressure of the air inside the ball is ... the temperature of the air inside the ball. This is obvious, once you think about it. You can NOT use the external air temperature to predict the pressure inside the ball, unless the ball has equilibrated to the external air for a LONG time. And NOBODY measures the temperature of the air inside the balls at this time.
- The air inside a warm, dry ball cools down relatively quickly when exposed to cold, wet conditions. This is principally because water has a much higher heat capacity than air does, and a drenching rain keeps exposing the outside of the ball to new, cold water. (The thin layer of water on the surface of the ball doesn't heat up.) And because the leather absorbs the cold water into itself.
- The air inside a cold, wet ball brought into a warm dry room takes many, many hours to warm up. For all the reasons inverse to those listed in 3 above. The football is a damn good thermos, surrounded by a dense layer of cold water (in the leather), and the air doesn't transport heat to the surface of the football very quickly. (Not nearly as fast as a dousing cold water will take it away.) For comparison, if they had doused the outside of the ball with warm, room temperature water, THEN it would have warmed up almost as fast as the cold water cooled it off.
- Every single football ever used by the NFL (or college, high school, Pop Warner, etc) behaves exactly as described in 1. above, if exposed to those temperatures & pressures.
- The fact that a football loses pressure in cold water is surprising to many people. The precise AMOUNT of pressure that it loses is surprising to LOTS of people. Including NFL players, league officials, referees, etc.
- Nobody in the Pats organization knew how to calculate the expected pressure drop. Nobody in the press knew how to do it. And therefore everyone was astonished at the expected number. Whether that number was 11.0 psi or 10.5 psi.
- All the reports of some balls having some pressure changes, while other balls have different ones is utter nonsense. (except in the case of a ball springing a leak, which no data supports.)
The simple fact is that the NFL had (prior to this incident) very close to zero knowledge about the interaction between pressure & temperature inside footballs. This is indisputable, simply by reading their pressure inspection procedures.
And I'll go with Occam's Razor on this issue. The simplest explanation ...
Which is simpler?
- The temperature difference is responsible for 1.5 psi pressure drop & there is a someone in the Pats organization that is letting 0.5 psi out of every ball, or
- The temperature difference is responsible for 1.5 psi pressure drop & the person making the statement did not know that TB likes his footballs set to 0.5 psi under the nominal. (A fact that he did not reveal until 2 days AFTER the quote came out.)
So, this is a question that I'd like answered by the Well report. There are several others.
I've started a thread listing the questions that I'd like answered.
Any suggestions you'd have would be very welcome.