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I Force of a Punch to exceed the Max Static Friction Force

  1. Aug 31, 2018 #1
    I heard that the average professional boxer's force of punch is between 500-750lb.

    If the coefficient of static friction of rubber (from shoes) to say concrete is at most 0.85 then why can boxers get hit (especially in the chest) without losing footing?

    Does it have something to do with the stance to increase the normal force? Or is it that when the boxer does not lose footing, the striking force was LESS than the normal force?
     
  2. jcsd
  3. Aug 31, 2018 #2

    jbriggs444

    User Avatar
    Science Advisor

    A boxer can lean in or be pushed back without having his feet move. The force of the punch is brief. The force from the floor can be longer lasting.
     
  4. Aug 31, 2018 #3

    anorlunda

    Staff: Mentor

    I would guess that the boxer's mass (intertia) must also play a role, and that a boxer standing on ice (say zero friction) could still deliver a significant fraction of that punch force.

    The physical key is the time element. If the maximum force lasts only a very short time, then inertia plays a bigger role. For longer times, then friction plays a bigger role.

    See if can find a plot of a boxing punch force versus time.

    If you include the bio metrics, it becomes very complicated. http://boxingscience.co.uk/explosive-training-boxing/
     
  5. Aug 31, 2018 #4

    russ_watters

    User Avatar

    Staff: Mentor

    No, one also needs to consider the duration or distance over which the force is applied - which also makes the force itself pretty meaningless.

    Momentum or energy transfer would be more useful.
     
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