Deflategate Question....Temperature changes??

Not 2 lbs psi difference, and one would expect the balls on the other side of the field to have the same/similar reading.

Try again.

objectivist wrote:

We have heard how Brady prefers balls inflated to the league minimum psi at most. What if the balls were in a warm environment (equipment room) at league minimum PSI. They then are moved to the field where it is well below freezing. Will that change of temp cause a change in PSI due to the effects of temp on the leather ball??

Not even close. I posted this on a another thread, but if the ball started at 70 F (room temp) and 12.5 psi, it would have to cool to -15 F to lose 2 psi. Conversely, if a ball is found to be at 10.5 psi at 50 F (conditions during the first half), it would have had to be heated to 173 F in order to pass inspection.

There is no way either of those scenarios happened.

Check the math if you like.

PV = nRT

V, n and R are constant

so P1/T1 = P2/T2

T2 = P2/(P1/T1)

P can be in any unit of measure, but T has to be in K.

The air inside the balls would be greater than 70 F. Compressing air will increase the temperature.

Assuming that a ball is 12 square inches, wouldn't inflating it to 12.5 pounds per square inch make the ball 150 pounds? Pretty sure no team does this, so I'm not sure why NE is getting criticized.

PV=nRT wrote:

The air inside the balls would be greater than 70 F. Compressing air will increase the temperature.

True but the math still holds, it would have to reach >170 F in order to cause that much deflation. A 170 F ball would be too hot to touch.

objectivist wrote:

We have heard how Brady prefers balls inflated to the league minimum psi at most. What if the balls were in a warm environment (equipment room) at league minimum PSI. They then are moved to the field where it is well below freezing. Will that change of temp cause a change in PSI due to the effects of temp on the leather ball??

It was 51 degrees on the field, not well below freezing. Good job though, you almost cracked the code.

The 2 psi is a sloppy number: a single digit of accuracy. It could be anywhere from 1-3 psi.

They probably use a good sized compressor to inflate the balls.

One possibility is that someone on the team knows that using heating the air prior to starting compression will lead to a lower psi ball as the temperature cools. This is what I think happened. The NFL needs to set a set both a psi, AND a temperature requirement to prevent use of "pre"heated air.

All of this assumes that the balls were 2 PSI under the league minimum of 12.5. No one has substantiated that rumor.

We do know that Brady stated that he likes them at 12.5; the refs inflated them to 12.5 during halftime; Brady second half stats were great.

neanderthal dream wrote:

Check the math if you like.

PV = nRT

V, n and R are constant

so P1/T1 = P2/T2

T2 = P2/(P1/T1)

P can be in any unit of measure, but T has to be in K.

V is not a constant. If you put a balloon in the freezer it will shrink.

I'm pretty sure... wrote:

neanderthal dream wrote:

Check the math if you like.

PV = nRT

V, n and R are constant

so P1/T1 = P2/T2

T2 = P2/(P1/T1)

P can be in any unit of measure, but T has to be in K.

V is not a constant. If you put a balloon in the freezer it will shrink.

But a football is not a balloon. It is much more rigid and will hold its shape better. 10 psi is a long ways from being flat, so constant V is a good assumption.

PV=nRT wrote:

One possibility is that someone on the team knows that using heating the air prior to starting compression will lead to a lower psi ball as the temperature cools. This is what I think happened. The NFL needs to set a set both a psi, AND a temperature requirement to prevent use of "pre"heated air.

I really don't think the preheated air theory holds up. It's too complicated. Letting air out is way easier and more precise to get your target psi than fiddling with heated air.

Think about it. Can you even buy a heated air compressor? And if you can, since the ball is at room temp, you'd have to hit it with air hotter than the 170 F PV=nRT predicts to compensate for the loss of heat to the leather and the surrounding environment.

Furthermore, the balls would have to be inflated with this hot air either immediately before or during inspection so that they don't end up at 170 F. That would be a little too obvious if the ref burns his hands on the footballs. So how long does an inspection take? There are 12 balls that all have to be weighed and pressure tested, and during this entire process the leather would be getting hotter and hotter as the heated air and balls reached equilibrium. How long would that take? Less time than the inspection lasts? In which case the balls would feel hot to the touch and/or would fail their psi test if they cooled too much.

Too many uncontrollable variables for the heated air idea to work. The air was let out. There is no other reasonable explanation.

"Can you even buy a heated air compressor?"

No need. Simply connect a duct to the compressor and run the duct to the back end of an air conditioning unit.

The deflategate issue is a joke.

It has been confirmed that none of the so called deflated balls were used in the second half.

first half score: 17 vs 7

Second Half score : 45 vs 7

so 28 zip in the 2nd half with the "perfect" balls.

Just let it go!!

neanderthal dream wrote:

Check the math if you like.

PV = nRT

V, n and R are constant

so P1/T1 = P2/T2

T2 = P2/(P1/T1)

P can be in any unit of measure, but T has to be in K.

The ideal gas law is not particularly accurate as temps drop and pressure increases.

objectivist wrote:

We have heard how Brady prefers balls inflated to the league minimum psi at most. What if the balls were in a warm environment (equipment room) at league minimum PSI. They then are moved to the field where it is well below freezing. Will that change of temp cause a change in PSI due to the effects of temp on the leather ball??

Nope

Chemical Ali wrote:

The ideal gas law is not particularly accurate as temps drop and pressure increases.

At the values we're talking about? It's good enough. Point being the balls would be either very hot or very cold for temperature to explain the discrepancy.

Angry4nothing wrote:

The deflategate issue is a joke.

It has been confirmed that none of the so called deflated balls were used in the second half.

first half score: 17 vs 7

Second Half score : 45 vs 7

so 28 zip in the 2nd half with the "perfect" balls.

Just let it go!!

If you think it's about the score difference, I'm sorry for you.

Angry4nothing wrote:

first half score: 17 vs 7

Second Half score : 45 vs 7

so 28 zip in the 2nd half with the "perfect" balls.

Just let it go!!

It's only cheating if he would have played worse.