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Old 08-22-22, 10:55 AM
  #44  
Yan 
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If you fill a glass with water, it's the same amount of water whether you drip it in slowly, or fill the glass in a few big pours spaced out in time. Dripping continuously vs several big pours does not have any effect on how fast water evaporates out of the glass. Whether water happens to be dripping into the glass at any given moment has no effect on the way water evaporates out. As long as there is some water in the glass, it's evaporating out at the same rate no matter what you do. The drops of water dripping in are not a magic blanket preventing evaporation.

I don't know why you're so caught up in your magic blanket theory. It's simply plain wrong.

Originally Posted by cyccommute

Your analysis if flawed. It’s the same energy but not the same temperature. That’s because there is a significant amount of time where no heat is being put into the wheel during braking with pulse braking. I agree that the amount of energy put into the system is the same but there are long periods of no energy input. Constant braking doesn’t give the same effect. In general, people who overheat rims generally practice your constant force braking, aka dragging their brakes. You’ve stated that you have melted pads. I’ve never melted a pad nor even gotten close to overheating a rim.

I have never said that. But I have said that constant input of heat from friction causes heat to build more than if there are large intervals of no input. Both rims will radiate heat but the constant braking scenario can’t shed heat faster than it is input. If you can’t shed heat faster than it is input, the heat builds up faster. The heat is additive. As you pointed out above, friction is equal to the coefficient of friction X the normal force. If there is no normal force (i.e. the brakes are off), there is no friction.

I don’t like your food analogies. A biological unit is different from a non-biological unit.

We don’t need an analogy because we have an excellent example right here. Your problem is that you are confusing “heat” with “temperature”. They aren’t necessarily the same thing. You can have the same amount of heat put into two systems but end up with two different temperatures based on the rate.
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