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-   -   Friction for different contacts (http://www.physicsforums.com/showthread.php?t=674568)

sriram123 Feb26-13 04:45 AM

Friction for different contacts
 
Hi all,
I know this is a very basic question and has been discussed in various threads.Anyway i would i like to ask this.

If the value of friction only depends on coefficient of friction and normal force, why is rolling friction less than sliding friction? Is it because the value of Rn the reaction force changes?

I know this is very elementary but I thought it would make my understanding better.

Thanks in advance

tiny-tim Feb26-13 05:44 PM

hi sriram123! :smile:
Quote:

Quote by sriram123 (Post 4286260)
If the value of friction only depends on coefficient of friction and normal force, why is rolling friction less than sliding friction? Is it because the value of Rn the reaction force changes?

"rolling friction" isn't actually friction, it's a loss of energy caused by continual deformation of the wheel where it meets the surface :wink:

from the pf library:
Friction:

Friction at the point of contact of a rolling body is static friction.

There is also a rolling resistance, or "rolling friction": an additional small force, caused by deformation of the body (in exam questions it can usually be ignored).

Friction at the point of contact of a sliding body is of course dynamic friction.


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