1. The problem statement, all variables and given/known data There's no specific problem statement but I have to explain how I would find out the coefficient of kinetic friction given the angle (θ) of the inclined plane and mass of the object sliding down, nothing else. 2. Relevant equations ƩF = ma μk = Fk (kinetic friction) / Fn (normal force) 3. The attempt at a solution I split the Fg (Fg = mg; weight) vector into x- and y- components so I could determine Fn (normal force). As a result, Fn = mgcosθ. And the force that moves the object downhill (I don't know what to call this) = mgsinθ. Now, to determine μk I know I must find Fk (kinetic friction) first. Using μk = Fk/Fn, Fk = μk*Fn which = μkmgcosθ. So, ƩF = (force that moves object downhill) - Fk, ƩF = mgsinθ - μkmgcosθ ; mg's cancel each other. Therefore ƩF = sinθ - μkcosθ, and ƩF = ma, so... ma = sinθ - μkcosθ. I then isolated μk (*I don't know if I did this correctly) * μk = ma - sinθ / -cosθ ? After doing all of this, I found out that I have all the variables except for ACCELERATION... and a = ƩF / m which I can not solve for! Can I just say that a = 0? I have no idea what to do.