Find the coefficient of static friction help?

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Discussion Overview

The discussion revolves around a homework problem involving an object on an inclined plane and the determination of the coefficient of static friction based on the angle at which the object begins to slide. The scope includes mathematical reasoning and conceptual clarification related to static friction and forces acting on an inclined plane.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Conceptual clarification

Main Points Raised

  • One participant expresses uncertainty about how to begin solving the problem, noting that they only know the angle at which the object begins to slide.
  • Another participant states that knowing the mass of the object is necessary to solve the problem, suggesting that without it, the problem is impossible to resolve.
  • A participant mentions advice from a teaching assistant (TA) who suggested using a variable for mass (M) and indicated that it might cancel out in the equations, although the participant remains confused.
  • A later reply reiterates the TA's suggestion, emphasizing that the object is at the verge of sliding at 35 degrees and that the maximum static friction force balances the weight component down the plane, correcting an earlier reference to kinetic friction.

Areas of Agreement / Disagreement

Participants generally agree that the mass of the object is a critical factor in solving the problem, but there is uncertainty regarding the approach to take. Multiple views on how to handle the mass and the equations remain present, indicating that the discussion is not fully resolved.

Contextual Notes

There is a lack of consensus on the necessity of the mass for solving the problem, and the discussion includes potential confusion regarding the distinction between static and kinetic friction.

rich6490
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Homework Statement


An object rests on an inclined plane. One end of the plane is lifted until the object begins to slide. If the angle at which the object begins to slide is 35 degrees, what is the coefficient of static friction?


Homework Equations


Possibly Fk=("mew"k)N


The Attempt at a Solution


Not even sure where to begin, just knowing the angle can I even solve this problem. Thanks for the help I really appreciate it.

Zach
 
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You need the mass of the object at the least to solve the problem. Otherwise, this is an impossible problem.
 
I talked to a TA at my college, he wouldn't really help me but he said its not that bad of a problem, and to just plug in M for mass, and hope it cancels out when you solve the equations. I'm still a bit confused, so anyones input is greatly appreciated. Thanks a lot.
 
rich6490 said:
I talked to a TA at my college, he wouldn't really help me but he said its not that bad of a problem, and to just plug in M for mass, and hope it cancels out when you solve the equations. I'm still a bit confused, so anyones input is greatly appreciated. Thanks a lot.
Yes, the TA is correct. The object is just on the verge of sliding , but still at rest, when the angle reaches 35 degrees. Therefore, Newton 1 applies, where the max friction force up the plane, F_s =(mu)_s(N) (not F_k or mu_k, which you have incorrectly noted) is balanced by the object's weight component down the plane. Hope that the M cancels when you solve the equation.
 

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