Static equlibrium with friction

AI Thread Summary
To solve for the normal force and the minimum force F needed to keep a 4.0 kg block from sliding down a wall with a coefficient of friction of 0.35, the equations of static equilibrium must be applied. The force F makes a 30° angle with the vertical, creating a relationship between the vertical and horizontal components of the forces. The equations Sum Fx = 0 and Sum Fy = 0 must be utilized to express the forces in terms of the normal force and friction. By incorporating the angle into the calculations, both the normal force and the minimum force F can be determined. Properly applying these principles will yield the required values to maintain static equilibrium.
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Homework Statement



a 4.0kg block is held against a brick wall and is just kept from sliding down by the force F. The coefficient of friction is 0.35 between the block an d the wall.

Find the normal force and the minimum force F that will keep the block from sliding.

block.png


Homework Equations



Sum Fx = 0
Sum Fy = 0

The Attempt at a Solution



Fx=Fnormal
Fy+Ffriction=mg

uFx=Ffriction

Fy+uFx=39.2
 
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Hi canicon,
Your equations are correct, but one is missing.
It is given that the force encloses a 30° angle with the vertical. That means a relation between Fy and Fx. What is it? Adding this relation to the other equations, you can get Fx and Fy.
ehild
 
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