Wednesday, January 21, 2015

Can Chemistry Save the Patriots?



I'm going on record as saying the Patriots are definitely guilty of using footballs that were below the required PSI by the NFL. I'm a little conflicted about how bad that is, as I'm really not sure about the details of the ball-checking process -- or if other teams do this normally -- but suffice to say, the Patriots were outside the rules for reasons that are totally unnecessary, thus tainting their legacy further.

HOWEVER, there's been some talk about how the weather can affect the pressure inside a football. I want to do some sweet calculations and see if there's any credibility to this line of thinking. I'm not a chemist, like some special guests I know, but I'll take a crack at this. Our special guest can feel free to comment if I'm wrong (or right!).



According to NFL rules, 12 balls are supplied by each team for their use on offense. Eight other balls, for the kicking game, are shipped from the manufacturer  and inspected in the referees' locker room 2 hours and 15 minutes before the game. One can assume that all balls are inspected at the same time in the referees' locker room. I can't find any info on the specific referees' locker room at Gillette Stadium, but one can assume that it's an indoor heated room. Again, this assumption may be incorrect. But if we do assume that, let's say that room is approximately room temperature, and for our purposes, I'm going to say that's 70 degrees Fahrenheit.

At the time of D'Qwell Jackson's interception, which prompted the investigation into deflated balls, the temperature at Gillette was between 45 and 50 degrees. Let's say it was 48.

If we want to calculate the exact pressure inside the footballs, we have to use THE GAS LAWS, especially everyone's favorite, PV = nRT. If T (temperature) goes down, and n (number of moles of gas in the ball) and V (volume) stay constant -- which they would assuming there was no deflation -- then P (pressure) would go down as well. With all this in mind, if we want to compare the pressure indoors with the pressure outdoors, we can cancel V, n and R because they would remain the same across the comparison, and we end up with P1 / T1 = P2 / T2. And if we want to solve for P2, that means P1 X T2 / T1 = P2. Right?

Let's consider the absolute pressure on a football. Firstly, let's assume the Patriots inflated the ball to minimum PSI allowed by the NFL, which is 12.5. That pressure, along with regular atmospheric pressure of about 14.7 psi, means that the P in our equation for a minimally allowable deflated ball would be 27.2.

So now we have our three variables: the temperatures inside the referees' locker room and on the field, and the pressure on the ball that would be inflated to a legal level. Is that 22-degree-Fahrenheit difference enough to reduce the pressure in the balls by 2 PSI, which is what the league found? Let's find out.

P2 (pressure of ball outside) = 27.2 PSI X 45 degrees F / 70 degrees F

P2 = 26.1 PSI

What we see is a reduction of 1.1 PSI, shy of the 2 PSI needed to approximately exonerate the Patriots of cheating.

I'm ready to say that temperature alone could not have accounted for this. This could mean a number of things: the referees didn't carefully measure the balls' PSI before the game and they were already below 12.5 PSI before the game, the Patriots deflated them after they were thoroughly checked, some other physical phenomenon is at play that I'm not aware of (quite possible!), or my calculations/assumptions here are pretty off (also quite possible!).

The fact is that this is incredibly embarrassing. The Patriots are very likely to have intentionally done something wrong, and were dumb enough to get caught. The Super Bowl is tainted, and it's another justifiable reason to pile on against the Patriots. I'm glad they're in the Super Bowl, and I know most fans would kill to be in the position I'm in now, but geez. The Patriots are good enough to win without whatever marginal benefit this small deflation gave them. No one is questioning that. So why bend the rules when you don't have to? TO MAKE ME INSANE THAT'S WHY.

1 comment:

  1. The real question is whether a football can be put underwater. Is 12.5 PSI enough pressure to declare a football water resistant?

    ReplyDelete