# 2014 Game Ball Damage

I’d recommend just using an exercise ball and ordering a new one tbh, we had no luck successfully patching ours, the tear just continued to get bigger.

Could you say what RPM you were using when the ball popped so those of us who have yet to pop ours know what is “too fast”?

I’d rather have a smiley face ball personally.

It’s not simply RPM. It’s compression, wheel diameter, tread material, number of wheels, wheel placement (angle of contact with ball), ball inflation, random factors (hit the seam or the zipper the wrong way), etc etc etc.

Well, here’s a photo of one of our prototype shooter wheels, and we did eventually pop the ball. But we repaired it (the ball) with a bicycle patch kit.
:rolleyes:

Thanks Don. You made my day.

The real question is, did it improve grip?

Very funny. Do you really expect us to believe that?

That you used a bicycle patch kit.:rolleyes:

Don, do you have any numbers on the coefficient of friction between your wheel and the ball?

coefficient of friction: 1.000000…1
Yup, broke physics

I feel like this is a joke, and I totally don’t get it at all. Do you think it is impossible to have a coefficient of friction >1? And that since your number is just marginally greater than 1, that you have broke physics? Well, hate to break it to you, but there are combinations of materials with coefficients of friction >1.

I’m probably just misunderstanding what you are saying though, so would someone kindly explain what he was trying to say?

It is possible to have something with a greater coefficient than one? I honestly didn’t think its possible mainly because anything greater one would mean you get more force out than you put in. Because the force of friction=Fn*coefficient of friction. Friction can only oppose up to the magnitude of the force being applied. If the magnitude of the force of friction were greater than the force it opposed, that would mean that friction itself was causing one or both of the surfaces to accelerate. I did not think that was possible since it breaks the law of conservation.

rough top tread is the best example that comes to mind that is frc applicable. i believe that some rough top tread has a coefficient greater then 1. think about Velcro the hook and loop take a LOT more then the normal force to get the 2 to slide against each other. and other surfaces can have similar interactions

Ok I looked it up. I think I get it now. My bad for the failed joke

That’s all right, it is a little bit counter-intuitive. Hey, but now you have learned some more physics, and who here doesn’t want to learn more physics!

There are other cases besides friction where you can “get more force out than you put in”. Gears are an excellent example of this. The important thing to remember is that there is no “law of conservation of force”. The important conservation laws are those of mass, momentum, and energy.

The other tricky thing with static friction is that the maximum force that static friction can provide is your stated equation. Static friction can always provide less force than this, but never more. If the applied force is less than the maximum force from static friction, then the force from static friction will be equal and opposite to said force.

Anyway, you probably knew most of this anyway. It is still a good refresher for me though. Since this is a thread about ball damage…um…don’t use spikes to get a greater CoF.

Lol ok:D