Homework Help: Friction Force Question Help!

1. Oct 15, 2011

jonochui

1. The problem statement, all variables and given/known data

The following questions are in regard to the situation where you press an apple crate against a wall so hard that the crate cannot slide down the wall.

a) What is the direction of the static frictional force (fs) on the crate from the wall?
b) What is the direction of the normal force (FN) on the crate from the wall?
c) If you increase your push, what happens to static friction (fs)?
d) If you increase your push, what happens to force normal (FN)?
e) If you increase your push, what happens to fs, max?

3. The attempt at a solution

a) horizontal towards you
b) horizontal away from you
c) no change
d) increase
e) remain the same

2. Oct 15, 2011

DukeLuke

Drawing a force body diagram and setting the sum of the forces in each direction equal to zero might be helpful, because some of these are wrong. It may help visualize the direction of the forces. Also remember the relation between the normal force and the magnitude of the static frictional force is $f_s = F_N\mu_s$

3. Oct 16, 2011

jonochui

I got it. THANKS A LOT~