Ok, a little experiment! Ok, so I want to test the coefficient of static friction for two different kinds of shoes. I'll be using a runners and a formal dress shoe. Is this an ok procedure? I'll using a wooden cherry board, and placing that against a wall. I'll slowly increase the angle of the board until the shoe in question slips. I'll measure the angle by placing a piece of paper at the side of the board and using a protractor. I'll do this a few times for each shoe to get an avg angle. I'll also have a scale for weighing the shoes. Hope you see what I'm trying to do here :rofl: Then I'm lost... So to summarize: What I have to work with: board two kinds of shoe soles protractor paper scale Now, my question is: the formula for static friction is F=uN. How can I find the u when I have two unknowns? I know N=mg, which I have but what about F?