Originally Posted by waterbug_wpb
Originally Posted by MN3
(although i would think the cold would shrink the ball, thus increasing the internal pressure)


Back to the PV=nRT, I think the gas (air) inside the ball would change more dramatically than the tension of the "pigskin" (actually cowhide, but whatever).

So the ball is filled by pumping air into it (generating some heat within the ball) under "ambient conditions" (78 deg F./ 60% RH).

We will assume that the air volume (amount of air originally introduced) remains constant. In addition, we'll assume the ball exterior remains constant (if it were horribly deflated, someone would have noticed)

Ball then goes to playing field which is quite cold (compared to 78 degrees ambient temp). Temperature of air inside ball is reduced.

Since we're assuming the volume of the ball remains (somewhat) constant, the Ideal Gas law above would indicate that the pressure is reduced according to the formula, proportional to the temperature reduction.


I think that they were pumped up in the sauna and then put into play. grin

How much of a difference would it make for the balls to be slightly deflated? At some point they would become harder to throw. Everyone is acting like it makes a giant improvement to have them slightly deflated.

And of course the Colts balls were properly inflated; you'd better check that before you complained!

Kent
1988 H16