(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

from the free body diagram of a block resting on a flat surface, I am trying to derive the coefficient of static friction.

2. Relevant equations

3. The attempt at a solution

I have the definition of the coefficient as:

u_{s}=F_{n}/F_{fr}

But in my free body diagram i am pulling on the block, which resists with the F_{fr}

I have

[tex]\Sigma[/tex]F_{x}=0

F-F_{fr}u_{s}=0

u_{s}=F/F_{fr}

My confusion is because if the definition of the coefficient is above, why don't I derive it when I observe my free body diagram of the block. What am I missing?

The forces in the x direction are my pulling force and the friction force that resists it * u_{s}

How do i get the weight of the block into my derived equation?

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Static friction co-efficient

**Physics Forums | Science Articles, Homework Help, Discussion**