Static friction is my answer correct?

  • #1
Femme_physics
Gold Member
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Homework Statement



What's the max weight, P, you can hang on the hanger's arm, when the hanger arm is attached to a pole with the help of two friction forces at point A and B.

http://img543.imageshack.us/img543/8466/maxwqeight.jpg [Broken]


Homework Equations



Static friction coeffecient = 0.2
L = 0.5 [m]
d = 0.1 [m]

The Attempt at a Solution



Attached here... I didn't use all the equations but I wrote them anyway
 

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Answers and Replies

  • #2
nvn
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Homework Helper
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Dory: Nice work. Your current answer is incorrect. Hint 1: By symmetry, Fsb = Fsa. Now you have three unknowns, and three equations. Hint 2: Fs does not necessarily equal mus*N. Try again.
 
  • #3
Femme_physics
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Thanks for replying, nvn! I was actually told by my lecturer yesterday that this question is actualy super hard since there is an angle between to two Na's and he's only gonna teach it after kinematics...from some reason he decided to put it in the exercise book to "challenge us" but he never told us it's super hard and takes a lot of thought... I personally thought it seems easy and can be solved with basic static rules... but I guess I'm wrong?.
 
  • #4
nvn
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Femme_physics: You are right; it is solved with statics.
 
  • #5
Femme_physics
Gold Member
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Ah...then peculiar why would he say it's so complicated when it's not. I'll try again later.

I like your usage of my new nickname, nvn :) though annoyingly longer, at least I don't sound like a Tolkien's dwarf.
 

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