Physics department chair at BC: weather alone could easily deflate ball from 12.5 to 10.5 psi

patriot1136 said:

Someone please tell me exactly what Rodgers said

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Froob said:

Changed my mind about a lot of people through this thing. Used to like Mort, Jackie Mac, Jerry Rice, and Jerome Bettis. But, now, **** EM. Wish I could go boo the **** out of Jackie at the Ace Tickets studios right now.

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PatSunday said:

I already posted the most obvious explanation.

First, the 3rd party video I posted shows that a Wilson football drops from 13 PSI to 9 PSI in just 30 minutes when brought outside from a guy's basement to a chilly outdoors, as measured with digital and manual temperature readers and air pressure gauges and pump. In theory the air pressure may drop to 10.5 PSI, but reality shows it can go far lower (this is even before you account that a wet ball would be even colder inside than a dry ball at the same temperature.)

More than malice, the clear and likely explanation is that the visiting team, the Colts, arrived with footballs in the luggage compartment of their bus and left them there until the referees asked to see them.

The luggage area is probably not heated. Also, luggage is below the passenger area, so there would be little heat transfer into the luggage part of the bus because heat travels upwards toward the roof. Finally, the bus was likely parked with the engine and heat off after the team arrived.

The Colts balls were likely left on the parked bus until they were needed by the referees for obvious reasons -- why bring them into the host's stadium. It was also raining heavily and there was a chance the rain could stop, so why get them wet --twice -- right before the game. Why carry 24 valuable footballs (12 of theirs, plus 12 optional the visiting team can bring) back and forth in heavy rain?

On the other hand, I doubt Bill or Tom keeps game footballs in the trunks of their cars or an outdoor shack. The host team (Patriots) obviously stores the balls inside and probably inflated them inside.

They inflated them to 12.5 PSI, because the NFL allows all quarterbacks to choose the pressure they like when they give the balls to the referees. Either the referees measured the Patriots footballs indoors (especially with heavy rain) or they were brought out to the referees outside shortly before they were measured, so they still had the right air pressure. In fact, with heavy rain or snow, and hours to kill before the game, I bet the referees will check the visiting team balls outside and the host team inside -- they don't need to do both simultaneously.

A drop of 4 PSI or less is well within the theory and 3rd party tests of what's expected. Additionally, the Patriots are not allowed to tamper with the balls (by heating or inflating) after the referees approve the starting air pressure. Then we would have InflateGate. And we already know the referees don't care about the air pressure between plays so I doubt they would hold up a play to add air to the ball at a quarterback's request (maybe in the future, but not in the past.)

Finally, at half-time, the referees obviously pumped more air on the field, not in a special room indoors, and it was cold outdoor air so the balls maintained pressure throughout. This proves the balls were not leaking air, and not faulty in any way. Finally, the balls lost pressure uniformly. If you wanted to cheat, you would inflate the balls at different levels and mark them, so you could pick and choose based on weather conditions during a particular hour.

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SVN said:

Still begs the question, who asked the pats to be investigated and how did they know to investigate ?

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tmajr3 said:

Hold on. Does anyone keep a room at 80 degrees? I don't think TB12 had the balls deflated, but come on. No one keeps a room that hot

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PatSunday said:

I'm sick of hearing theories, and I don't care if the guy has a PhD in Physics. Actual experiments show that a football in normal indoor temperature (low 70's) drops by 4 PSI when exposed to the outdoors (low 40's).

Simple mathematical equations only consider one part of the question. They also assume a rigid container. The quantity of air and its temperature "adds up" to how much psi is inside a ball, but there is also an obvious factor that a ball at 13 PSI is partially so because of the pressure a tight football exerts onto the air (it's not a rigid container). Let's say that 3 PSI (pressure per inch) of a 13 PSI inside the ball is contributed solely by the squeeze the stretched out leather puts on the air.

When inflating a ball, the first seconds don't even show much PSI. But the last few seconds of pumping a football bring the pressure rapidly from 10 PSI to 18 PSI. Why? It's not just the bit of air that adds the PSI, but the fact you're stretching a ball that's already at the brink, rapidly building pressure. A tiny bit of air will add 2 or 3 PSI in seconds when the ball or balloon is at it's biggest, even though there's actually the most amount of air in it.

When the temperature drops, air pressure in a container may also drop by 2 or 3 PSI according to theory, alone. But remember that the football stretches. Colder air molecules bounce slower and the ball appears deflated. But also, the stretch on the ball is reduced, so the ball itself now only gives 1 PSI extra instead of 3 PSI.

So while theoretically the air pressure might drop 2 PSI in theory, the air pressure inside the ball is not due to temperature alone, but also to the squeeze the ball pushes back on to the ball. A 2 PSI drop due to air pressure may also bring a "bonus" drop of 1 or 2 PSI due to the ball being relaxed and not contributing so much pressure, for a total of 3 or 4 PSI.

Simple models of the real world are always wrong. That's why they are models.

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PatSunday said:

I'm sick of hearing theories, and I don't care if the guy has a PhD in Physics. Actual experiments show that a football in normal indoor temperature (low 70's) drops by 4 PSI when exposed to the outdoors (low 40's).

Simple mathematical equations only consider one part of the question. They also assume a rigid container.

Make a rigid mold the same size as an inflated football (say, metal). Pump it full of air until it's at 5 PSI and later 18 PSI. The extra 13 PSI appears because of extra air (or because the temperature increased, or a mix of those causes).

But with a real football, the "balloon" of the ball is pushing back differently at different air pressures (and at low pressure, not at all since it's not stretched). When you pump it up from 5 PSI to 18 PSI, the PSI due to extra air or hotter temperature might be responsible for 11 PSI increase, but the extra 2 PSI due to "new" pressure. The leather pushes back, just like a guy squeezing a ball during the measurement will increase the PSI.

In reverse, a theoretical calculated expected drop of 2 PSI using a simple formula might actually be 3 or 4 PSI in real-life, if you start with a fully inflated legal football (as the Patriots did) that used to contribute maybe 2 PSI by the stretched leather alone, and now only contributes 1 PSI now that the air behaves differently and the leather can relax (numbers are examples).

Simple models of the real world are always wrong. That's why they are models.

If ideas on paper were the same as real-life tests, everybody would be a millionaire.

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Dr Pain said:

I said it before, the Colts wouldn't understand this because they are from a science denying state that plays in a climate controlled dome and the science behind it is the Gay-Lussac's Law and they won't look at anything that has gay in it.

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PatSunday said:

I'm sick of hearing theories, and I don't care if the guy has a PhD in Physics. Actual experiments show that a football in normal indoor temperature (low 70's) drops by 4 PSI when exposed to the outdoors (low 40's).

Simple mathematical equations only consider one part of the question. They also assume a rigid container.

Make a rigid mold the same size as an inflated football (say, metal). Pump it full of air until it's at 5 PSI and later 18 PSI. The extra 13 PSI appears because of extra air (or because the temperature increased, or a mix of those causes).

But with a real football, the "balloon" of the ball is pushing back differently at different air pressures (and at low pressure, not at all since it's not stretched). When you pump it up from 5 PSI to 18 PSI, the PSI due to extra air or hotter temperature might be responsible for 11 PSI increase, but the extra 2 PSI due to "new" pressure. The leather pushes back, just like a guy squeezing a ball during the measurement will increase the PSI.

In reverse, a theoretical calculated expected drop of 2 PSI using a simple formula might actually be 3 or 4 PSI in real-life, if you start with a fully inflated legal football (as the Patriots did) that used to contribute maybe 2 PSI by the stretched leather alone, and now only contributes 1 PSI now that the air behaves differently and the leather can relax (numbers are examples).

Simple models of the real world are always wrong. That's why they are models.

If ideas on paper were the same as real-life tests, everybody would be a millionaire.

A scientist's job is to make a hypothesis, and run an experiment. Not to plug-in variables into a very simple and generic formula and write an article. But, I am glad that the author wrote about it since the media are all ignoring this.

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kennyb said:

The ideal gas law doesn't actually assume a rigid container.

The calculations people are making do. And a rigid container would push back on the air to balance the pressure. If it didn't it would explode by definition.

If you assume the ball shrinks in cold weather that would tend to drive pressure UP higher than the calculations people are making. But I think this would be slight. Maybe leather expands with water who knows. That would drive pressure LOWER than calculations.

So yes they should do tests a day ball at 72 and a wet ball at 45. But the part about how the ideal gas law calculations need to adjust for the ball "pushing back" on the air doesn't make sense.

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*Furthermore, given that it was raining all day, the air in the stadium was saturated with water vapor. At 70 degrees, water has a vapor pressure of 0.38 psi. The total pressure of the ball is equal to the pressure of the air inside the ball and the vaporized water in the ball. At 49 degrees, the vapor pressure of water is 0.13 psi. Up to 0.25 additional psi can be lost if the balls were inflated by either the team or the refs prior to the game. Granted, it's unlikely that anyone would inflate balls from 0, but it easily could cost another couple hundredths of a psi in pressure.

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PatSunday said:

I already posted the most obvious explanation.

First, the 3rd party video I posted shows that a Wilson football drops from 13 PSI to 9 PSI in just 30 minutes when brought outside from a guy's basement to a chilly outdoors, as measured with digital and manual temperature readers and air pressure gauges and pump. In theory the air pressure may drop to 10.5 PSI, but reality shows it can go far lower (this is even before you account that a wet ball would be even colder inside than a dry ball at the same temperature.)

More than malice, the clear and likely explanation is that the visiting team, the Colts, arrived with footballs in the luggage compartment of their bus and left them there until the referees asked to see them.

The luggage area is probably not heated. Also, luggage is below the passenger area, so there would be little heat transfer into the luggage part of the bus because heat travels upwards toward the roof. Finally, the bus was likely parked with the engine and heat off after the team arrived.

The Colts balls were likely left on the parked bus until they were needed by the referees for obvious reasons -- why bring them into the host's stadium. It was also raining heavily and there was a chance the rain could stop, so why get them wet --twice -- right before the game. Why carry 24 valuable footballs (12 of theirs, plus 12 optional the visiting team can bring) back and forth in heavy rain?

On the other hand, I doubt Bill or Tom keeps game footballs in the trunks of their cars or an outdoor shack. The host team (Patriots) obviously stores the balls inside and probably inflated them inside.

They inflated them to 12.5 PSI, because the NFL allows all quarterbacks to choose the pressure they like when they give the balls to the referees. Either the referees measured the Patriots footballs indoors (especially with heavy rain) or they were brought out to the referees outside shortly before they were measured, so they still had the right air pressure. In fact, with heavy rain or snow, and hours to kill before the game, I bet the referees will check the visiting team balls outside and the host team inside -- they don't need to do both simultaneously.

A drop of 4 PSI or less is well within the theory and 3rd party tests of what's expected. Additionally, the Patriots are not allowed to tamper with the balls (by heating or inflating) after the referees approve the starting air pressure. Then we would have InflateGate. And we already know the referees don't care about the air pressure between plays so I doubt they would hold up a play to add air to the ball at a quarterback's request (maybe in the future, but not in the past.)

Finally, at half-time, the referees obviously pumped more air on the field, not in a special room indoors, and it was cold outdoor air so the balls maintained pressure throughout. This proves the balls were not leaking air, and not faulty in any way. Finally, the balls lost pressure uniformly. If you wanted to cheat, you would inflate the balls at different levels and mark them, so you could pick and choose based on weather conditions during a particular hour.

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Danger Zone said:

One calculation I saw on reddit briefly mentions the relative psi's of water vapor at different temperatures.

http://www.reddit.com/r/nfl/comments/2sxul5/deflategate_could_the_weather_have_an_effect_on/


I've wondered if the cooling effect of the evaporation of water off a wet football as it spins at high velocity would do anything to cool the football down below the recorded air temperature. Maybe there is a couple of a hundredths of a psi that could be lost from this effect if applicable?

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kennyb said:

Things only cool to outside temperatures not below.

Wind chill is what temp something feels like as it sucks heat from your body. But it doesn't actually lower the temp below the actual temp.

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bpippin said:

Why don't they use nitrogen to fill footballs, I believe nitrogen isn't affected by temprature

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BradyFTW! said:

http://nesn.com/2015/01/boston-college-professor-weather-had-to-play-role-in-deflategate/

If the balls were filled to 12.5 psi in an 80 degree room, then at 40 degrees they would eventually deflate to 10.5 psi. At least according to Michael Naughton, chair of the physics department at BC. Who is a Bills fan, btw, so no homerism here.

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