-> -----Original Message-----
-> From: Phys-l [mailto:phys-l-bounces@www.phys-l.org] On Behalf Of John
-> Denker
-> Sent: Thursday, January 22, 2015 9:22 PM
-> To: Phys-L@Phys-L.org
-> Subject: Re: [Phys-L] physics and football
-> http://static.nfl.com/static/content/public/image/rulebook/pdfs/5_2013_B
-> all.pdf
->
-> The trainer could swear "I inflated them to 12.501 and never touched them
-> after that."
->
-> ===============
->
-> I resent the tone of the Jack Andrade article that cheating by means of
-> physics isn't cheating.
I agree, especially since they didn't appeal to the lack of temperature specifications in the rules but said they didn't know what happened. If the Patriots org. had initially come out and said they didn't consider the under-inflation due to temperature effects to be a rules violation because there's no temp. spec. in the rules, I might put it down do shady loophole dealings. But now it's too late to appeal to weather effects, especially after Belichick and Brady made denials.
I guess someone could infer that the pressure (notice the rule uses pounds for the inflation unit; that's another problem) stated in the rule must be during actual play rather than at testing time, but that would mean the balls should be tested on the sidelines after equilibrating. The rule also says the balls will remain under supervision of the Referee until game time. I don't think the Referee wants to wait in <50F wet weather for 2 hours, and I don't think he wants to carry the balls back and forth.
Consider a stabilized gauge pressure of 12.5 psi, that's 27.2 psi absolute, at 75 deg. F. When I drop that to 50 deg. F isochorically I get 11.2 psi gauge. While under pressured, that's still not 2 psi down.
The NFL is going to have to tighten loopholes with people like Belichick around. Also, makes you wonder what the pressures of the balls supplied by the Colts were. And what happens to balls in Green Bay? Is the sideline pressure 12.5 psi?