Friction Equilibrium Problem: Solving for Minimum Coefficient of Friction

[Oblivion77]

Homework Statement

Homework Equations

Sum of forces in x,y and f/N=coefficient of friction

The Attempt at a Solution

I am not sure where to begin, I think each member there is a 2 force member. I already found the minimum coefficient of friction by doing Tan(8)

 

[Topher925]

Correct. What you now need to find is the force normal to the wall acting at point B. Sum the foces in the X and Y, you will have two equations with two unkowns. Finding the friction force is simply just the Y component at B.

 

[Oblivion77]

Correct. What you now need to find is the force normal to the wall acting at point B. Sum the foces in the X and Y, you will have two equations with two unkowns. Finding the friction force is simply just the Y component at B.

Thanks, would I need to use both members or can I only use the bottom member to find the answer?

 

[Oblivion77]

Correct. What you now need to find is the force normal to the wall acting at point B. Sum the foces in the X and Y, you will have two equations with two unkowns. Finding the friction force is simply just the Y component at B.

Are you sure that is correct? I didn't know the y component of the normal is the friction? If there was just the normal what would be the other unknown?

 

[Oblivion77]

anyone have any ideas? I tried some stuff, and got an answer as 9.15N. Not sure if that is correct.

 

[Oblivion77]

Still stuck on it.

 

[LogicalTime]

try and break it down into forces in y direction and forces in x direction

here is what I get for the y direction, T is the tension force
$T_{1} \cos (30^{ \circ }) + T_2 \sin( 8^{\circ}) -mg = 0$

try and get the x direction forces into an equation