PDA

View Full Version : What is the pressure of the inside of a tennis ball?


wings56
12-13-2005, 03:10 PM
Does anyone know what the pressure on the inside of a tennis ball is?? Not very important but I can't seem to find it online anywhere.

Prince_of_Tennis
12-13-2005, 03:47 PM
I'm pressure its just regular air.

Max G.
12-13-2005, 06:37 PM
I thought it was approximately 2 times atmospheric pressure.

Aykhan Mammadov
12-14-2005, 01:39 PM
If the pressure inside were less than atmospheric a ball would be bended inside itself.

If it were equal it'd be easy to bend it by a finger.

I also think it is definetly higher than atmospheric in such a degree that it's rubber surface prevents it to blow up. But since balls of different manufacturers vary in material/quality of their surfaces as well as in sizes I think pressure inside also vary from model to model.

Docalex007
12-14-2005, 04:58 PM
I thought it was approximately 2 times atmospheric pressure.

Not quite. The pressure inside an average tennis ball is circa:

Pressure (inside ball) = 1.2 atm

So the pressure inside the ball is slightly higher than ambient sea level pressure. This is good because most people play tennis in mild weather which decreases pressure inside the tennis ball due to loss of heat energy; thus slowing down air molecules inside the ball.

Remember, the amount of bounce you get back is directly related to how much energy the shell of the ball can store. And the compression maximum of the shell is directly related to how much the air inside the ball can be compressed.

35ft6
12-14-2005, 05:06 PM
The inside of a tennis ball feels a lot of pressure to get laid and be a real man.

Rumjungle
12-14-2005, 05:50 PM
At 1.2 absolute, wouldn't that be only 3psi of positive pressure? That's a lot less than I thought.

FedererUberAlles
12-14-2005, 05:54 PM
1.2 atm? Are you sure that is right?

Rumjungle
12-14-2005, 06:34 PM
3psi at that small of a volume doesn't sound right to me.

wings56
12-14-2005, 07:25 PM
The inside of a tennis ball feels a lot of pressure to get laid and be a real man.
haha!!

Geezer Guy
12-15-2005, 06:50 AM
I've heard that Rocky Mountain tennis balls feel less pressure New York tennis balls.
I think (I'm not positive, but I'm pres-sure) it's called the "John Denver Effect".

DJ Edwards
12-15-2005, 07:35 AM
Not quite. The pressure inside an average tennis ball is circa:

Pressure (inside ball) = 1.2 atm

So the pressure inside the ball is slightly higher than ambient sea level pressure. This is good because most people play tennis in mild weather which decreases pressure inside the tennis ball due to loss of heat energy; thus slowing down air molecules inside the ball.

Remember, the amount of bounce you get back is directly related to how much energy the shell of the ball can store. And the compression maximum of the shell is directly related to how much the air inside the ball can be compressed.

"My cat's breath smells like cat food" -Ralph Wiggum
"And so the doctor said I wouldn't get so many nose bleeds if I'd just keep my finger out of there"-Ralph again
"UHHHHHH, what?"-Butthead

Do you get the Simpsons there in BRD?
Is everyone in Deutchland a scientist?
"Batman's a scientist." (Homer's remark, monorail episode, circa 1992)

Seriously though, what's the deal then with the pressure-less balls?

Docalex007
12-15-2005, 08:37 AM
At 1.2 absolute, wouldn't that be only 3psi of positive pressure? That's a lot less than I thought.

Tennis ball physics people:

The inside of the tennis ball does indeed have roughly on average 1.2 atm pressure. This is about 17.6 psi.

Ambient pressure or sea level pressure is around 14.6 psi so we have a net pressure of 3 psi inside the ball pushing on all sides from within.

PSI= pounds/in^2 or pounds per square inch.

So what this means is every square inch on the surface of the ball can support 3 pounds of raw force before giving in. Try it with your thumb because your thumb is roughly 1in X 1in. Press down and apply pressure gently until the shell of the ball begins to give in....you are now applying around 3 full pounds of force.

Remember, air is a gas and gas is a type fluid. A fluid can only be compressed so much before it reaches its limit. Since the entire ball is filled with an evenly distributed volume of air, the compression limit is quickly reached when we try to press in on the ball. (this is obvious stuff).

Just to make it known if its not already....you can play tennis without problems using pressureLESS balls. These balls have 0 psi net pressure....meaning they have ambient pressure inside. Therefore, pressurized balls at 3 psi shouldn't be all that hard to imagine.

Docalex007
12-15-2005, 08:45 AM
3psi at that small of a volume doesn't sound right to me.

Remember, 3 psi in a small volume and space is the same as 3 psi in a giant balloon. It makes no difference....psi is psi.

Which means it would still take 3 pounds of force to push in an area of one square inch.

Docalex007
12-15-2005, 08:54 AM
"My cat's breath smells like cat food" -Ralph Wiggum
"And so the doctor said I wouldn't get so many nose bleeds if I'd just keep my finger out of there"-Ralph again
"UHHHHHH, what?"-Butthead

Do you get the Simpsons there in BRD?
Is everyone in Deutchland a scientist?
"Batman's a scientist." (Homer's remark, monorail episode, circa 1992)

Seriously though, what's the deal then with the pressure-less balls?

I seriously do not get the first half of your post. And where or what is BRD?!

What about pressureless balls? Remember, they are called pressureless but still have 14.6 psi in them (which is ambient pressure). So since its not a vacuum, it will still bounce perfectly fine and ok, like I said before, gas can only be compressed so much.

Just for an interesting fact. The energy as it makes contact with the ground is stored in the rubber shell of the ball! Its because of this the ball bounces back at around 50-60% its original height. (meaning it lost 40-50% energy to the ground and as heat).

Imagine a world where 100% energy is conserved when a ball is dropped. What would happen? The ball would never stop bouncing.

DJ Edwards
12-15-2005, 10:01 AM
Not a Simpson's fan, huh? I know it's popular in France, thought it might be in Germany as well.

I'll mangle the spelling, but BRD was Bundes Republik Deutchland, not to be confused with the then DDR (Deutches Democratish Republik).

Following your extremely techical and scientific explanation of pressurized tennis balls, I thought juxtasposing a quote from one of the most brain-dead characters on the Simpsons, Ralph Wiggum, might derive a comic effect. Obviously I failed.

I'm currently working out the kinks to a quantitative theory on opponent perception in tennis. Once I have it down I post it and maybe someone can derive something out of it. Until then, I'll keep on enjoying the Paulaner exports and be more careful in my attempts to make humor.

Docalex007
12-15-2005, 03:49 PM
I'm definitely no Simpsons fan, rather a Family Guy fan. That has to be the funniest show ever created! How can you beat the characters of Stewie, Peter, Brian....I mean, c'mon!

I did get the Butthead one...that is after re-reading it. :) I've never watched Beavis and Butthead in my life. I'm not sure if we get the Simpsons here since I do not watch any tv whatsoever. The two or three shows I do watch I watch them on the computer. Shows like Conan O'Brian, Family Guy, The Daily Show.

"quantitative theory on opponent perception"? Whenever you get finished collecting all the data your gonna need, give it to me and i'll run random quantum analysis on it to make sure it holds true.

Maybe then we can answer the question: what IS perception?

Aykhan Mammadov
12-15-2005, 05:08 PM
Remember, 3 psi in a small volume and space is the same as 3 psi in a giant balloon. It makes no difference....psi is psi.

Which means it would still take 3 pounds of force to push in an area of one square inch.

Yes, it confuses people because strictly speaking pressure = Force/square, not mass/square. Pound is the same as kg with some koefficient = 0.4536, it is measure of mass, that is psi can't be measure of pressure. Strictly speaking u must tell "3 pounds of force" but then add: with acceleration "g" near Earth.

Docalex007
12-16-2005, 01:41 PM
Yes, it confuses people because strictly speaking pressure = Force/square, not mass/square. Pound is the same as kg with some koefficient = 0.4536, it is measure of mass, that is psi can't be measure of pressure. Strictly speaking u must tell "3 pounds of force" but then add: with acceleration "g" near Earth.

Your absolutely right. A pound is no measure of Force, but rather one of weight and is relative to the gravity Force wherever you are.

F = ma
Force = mass X acceleration
Force (newtons) = mass (kg) X acceleration (m/s^2)

a = 9.81 m/s^2

Psi is a sucky way of describing pressure. If the rest of the world can use units like Pascals then why can't the US?

1 pound per square inch = 6 894.75729 pascals

MackSamuelHustovisics
12-16-2005, 09:57 PM
Has anyone ever tried microwaving pressureless tennis balls to get more bouce? ( I know, what's the point. Just curious ) People do it to save money by extending the life of normal balls so I don't see how pressureless ones wouldn't work.

Oh yeah....make sure the balls aren't titanium reinforced or whatever other metal material if and when you microwave them!

wings56
12-17-2005, 08:55 AM
wow, never thought of microwaving a ball

doriancito
12-17-2005, 09:40 AM
i wouls like to know too but isnt the pressure measured in PSI ? pascals?