Re: 2014 Game Ball Damage
 

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?

Re: 2014 Game Ball Damage
 

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.

Re: 2014 Game Ball Damage
 

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

Re: 2014 Game Ball Damage
 

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

Re: 2014 Game Ball Damage
 

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!

Re: 2014 Game Ball Damage
 

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.

Re: 2014 Game Ball Damage
 

Lol ok:D

Re: 2014 Game Ball Damage
 

isn't that from your 35AD "Chariot Assist" game robot?

Re: 2014 Game Ball Damage
 

We popped a ball with a piece of Bosch. Fixed with Shoe Goop and a small piece of cotton cloth. The puncture was a 1/2" cut. We also bought a replacement bladder from Walmart (the Gold's Gym 65cm ball) This proved to be too small. The 75cm might work better. Actually the regular 65cm were suspiciously sold out, so we got the 65 stay put for 10 bucks more. The stay put was $10 of loose sand that took about 10 minutes to shake out! :D

We used a waterbed repair kit.

The ball is pvc, like waterbeds.

The bike patch will likely work for a short period of time, but will be leaky and fail over the course of a couple weeks of testing (good enough? I think it might be)

Re: 2014 Game Ball Damage
 

We haven't had any trouble with popped balls. Good job FIRST, for choosing a robust game piece.

Re: 2014 Game Ball Damage
 

Did you mean Shoe Goo?

http://www.chiefdelphi.com/forums/sh...3&postcount=10