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Coefficient of friction 
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#1
Nov1205, 11:33 PM

P: 1,237

If the coefficient of static friction between a table and a rope is [tex] \mu_{s} [/tex], what fraction of the rope can hang over the edge of a table without the rope sliding?
Ok, so I declared two variables, P and 1P . From here, all I know is that mass and weight are not of any concern in this problem. Could someone please offer some help in solving this problem? I know the answer is [tex] \frac{\mu_{s}}{1+\mu_{s}} [/tex] Thanks 


#2
Nov1205, 11:41 PM

P: 37

Are you sure the answer you have is right? i get something slightly different.
In any case, I think you should start by equating the two forces acting on your rope, [itex] F_g[/itex] and [itex]F_f[/itex]. You know that [tex] F_g=mg[/tex], where m is the mass that's hanging, and that [tex] F_f=\mu_s(Mm)[/tex], where M is the total mass With these equations in hand, you can now find the critical percentage, M/m. Hope it's useful, but once again, this leads to a different answer from that which you've got. 


#3
Nov1205, 11:42 PM

PF Gold
P: 867

Lets say that p is hanging of the table and 1p is on the table. Think how much force (mg) p is pulling down with and how much friction is resisting due to the 1p on the table. Then equate the two. Oops! once again I post a second after someone else!



#4
Nov1305, 03:06 AM

P: 183

Coefficient of friction
I agree with the answer that you are looking for Regards, Sam 


#5
Nov1305, 12:49 PM

P: 37

Sorry, my bad. 


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