how to find coefficient of kinetic friction... please?!! I am lost on this question, hopefully someone can help: a 300 kg crate is placed on an adjustable incline and as one end of the incline is raised the crate begins to move downward; if the crate slides down the plane at an acceleration of 0.7m/s2 when the incline angle is 25 degrees, what is the coefficient of kinetic friction between the ramp and the crate? I drew a free-body diagram and that's about as far as I got... I know that the kinetic friction force is in the opposite direction that the crate is moving, but other than that i'm lost... please help! Thanks!