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Is friction affected by heat?

  1. Nov 4, 2012 #1
    Does heat have any effect on friction in any other way than in lubricated friction when considering the three states of matter?

    Thanks,
    Any help will be appreciated!
     
  2. jcsd
  3. Nov 4, 2012 #2

    rcgldr

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    Depending on the material, kinetic (dynamic) friction decrease once temperature exceeds some level. This is why overheated brakes can fade, why overheated clutches can slip, and why overheated tires slide easier than cool tires.
     
  4. Nov 4, 2012 #3

    SammyS

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    Kinetic (dynamic) friction in some cases increases with heat. Take for instance brake pad material in some racing applications. It's fairly common for the driver to have to get heat into the brakes before they work at an optimal level.
     
  5. Nov 5, 2012 #4
    Thank you for your replies,

    I thought the coefficient of friction of rubber iscreased with the heat. Thus, the burn-out of tires before a drag race. Also, lubricants, like engine oil have less friction with higher temperatures,

    But generally speaking, does heat reduce or increase the coefficient of friction?
     
  6. Nov 5, 2012 #5

    rcgldr

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    There's an optimal range of temperature that varies depending on the material. If below the optimal temperature range, then heat will improve friction, if above the optimal range, then more heat will degrade friction. Once within the optimal temperature range, then the ideal situation would be to dissipate heat at the same rate it's generated (on average) so that temperature remains within the optimal range.
     
  7. Mar 24, 2014 #6
    Same goes with tires, which is why drag racers do burn-outs before a race. That's not just for show, the heat makes the rubber a more sticky.
     
  8. Mar 24, 2014 #7

    cjl

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    It also scrapes off the outer layer of rubber from the tire, exposing a fresh, uncontaminated, consistent surface on the outside of the tire.
     
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