# Friction Coefficient For Humans

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Is there a frictional coefficient for human beings?

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There would be no such single number since coefficients of friction depend on both surfaces in contact not just a single surface. Even the coefficient of friction for human on human would be variable depending on what parts of the humans are in contact, how much each human is perspiring, the presense of any lubricants, density of hair in the contact areas and so on.

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Sounds like this could be the beginnings of a fun experiment with the right human partner to test with.

...

I'm sorry, I couldn't stop myself.

But yes, what the above poster said is correct.

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Actually I was gonna use it for air resistance. lol!

I know it seems funny, but I would hate to use 0.3, as a typical coefficent, but it didn't seem right. 0.03 was way better. I guess 0.03 is alright. Thanks for trying though.

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Quote:
 Original post by Jacob RomanActually I was gonna use it for air resistance. lol!I know it seems funny, but I would hate to use 0.3, as a typical coefficent, but it didn't seem right. 0.03 was way better. I guess 0.03 is alright. Thanks for trying though.

It then depends on the direction of travel and the particular positioning of the human who is to be flung through the air. You could probably look up the terminal velocity of a skydiver in a spread-eagle position and calculate a coefficient from that given the density of air. That would work for any instance where the 'front' of your human is exposed to the airflow.

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Yes, have it change depending on their position if your game allows for that. Lower the friction and raise it between the acceptable levels depending on how much of their surface area is exposed to the downwards direction. Or, just make it increase/decrease based on the angle (which would be easier)

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First I pictured some poor guy skidding across the pavement. Now I picture him thudding into the ground. I can't say it's an improvement.

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Quote:
 Original post by LilBudyWizerFirst I pictured some poor guy skidding across the pavement...

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In my Physics w/Calculus class' book they used a simplified equation for drag. (I believe you're talking about calculating drag.) If I recall correctly, they used.... (think, think)

(for slow moving objects)
drag force = 1/4 (some drag constant)*v
(for fast moving objects)
drag force = 1/4 (some drag constant)*v^2
(for making it look right, I would assume)
drag force = 1/4 (some drag constant)*v^(some value between 1 and 2)

where "some drag constant" is calculated in square meters from an approximating, bounding rectangle from "in front of" the direction the object is moving.

Then you have to do some algebra and calculus to integrate the force->velocity->position

My understanding of friction was that
ƒ=μn
(friction force = friction coefficient * the normal force (force pressing the objects together) and actually has nothing to do with the speed the objects are travelling relative to one another.

Drag is velocity dependant, (but, being a force, affects acceleration, which integrates into velocity... so you have to do a little tricky algebra)

Anyway, I might be way off base, this post just triggered some physics class memories (from last term).
Someone please correct me if I'm wrong.

(Here are some wikipedia entries. I see that Coloumb's friction equation includes velocity... hmm, guess we didn't cover that in class. You'll notice down lower the equation for kinetic friction; that seems to be the one we used in class.
I think you might be looking for atmospheric drag)
Friction
Atmospheric_drag

-Michael g.

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Hello again Jacob...

The drag friction coefficient is lower when the surface is smooth and greater when it is hard...I know that for a car's surface (the metal parts, which are smooth) the coefficient is something like 0.3...for human skin for example, it is greater...maybe something like 0.5

Remember, the drag friction, the static friction and the dynamic friction coefficients are independent one from each other...

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