[MMaschin]

The climate change between the warm locker room and the field... 25 or 30 deg. (F), might account for 1 pound, but not 2.

But, I've seen a lot of press from QBs saying it doesn't make a difference to those who say it's huge. Which is it?


It's less than that.

Assuming the balls were inflated to the minimum of 12.5 PSI, in a room with a temperature of 70 degree's F. And the temperature of the air in the balls when they were checked at halftime was 50 degrees F - the air inside the ball most likely would not have dropped all the way down to ambient temperature, but for the sake of argument we can assume it did. The volume of the air in the ball would have dropped 2% for each 10 degree F drop.
http://www.engineeringtoolbox.com/air-temperature-volume-d_853.html

That means even a 20 degree drop in temperature would have resulted in a less than .5 (~0.495) PSI drop in the ball.

Brady is the one who confused me on being able to tell the difference. In one sentence he says he prefers a ball at 12.5 over 13.5 - so he can tell a difference of 1 PSI (8% difference), but later on he says he can't tell the difference between 12.5 and 10.5 (16% difference)? That's not very believable.


I really wish he would have simply said, "you know what, the ball did feel a little soft, but I knew they had gone through the pre-game testing, so I just figured they were OK". But he didn't. He said he couldn't tell the difference, and I find that unbelievable. So, in my opinion, Brady lied. And the only reason for him to lie, again in my opinion, is because he's hiding something.

[lepton]

Do you live in a vacuum?

I don’t mean a rhetorical one, but an actual physical one? If not then the pressure value for the equations is 27.2, for 12,5 PSI, since the football is surrounded by an atmosphere of pressure.

[norwaypinesavage]

Does your “Engineer’s toolbox” have a formula for how much the football’s leather stretches when it gets soaking wet in the rain?

[IamConservative]

That means even a 20 degree drop in temperature would have resulted in a less than .5 (~0.495) PSI drop in the ball.

Another factor to consider. A football is not a fixed size vessel. It is a rubber bladder inside leather. There is an amount of elasticity that would help maintain pressure when the gas loses some volume do to cooling.