1. The problem statement, all variables and given/known data The floor of a railroad car is loaded with loose crates, having a coefficient of static friction of 0.25 with the floor. If the train is initially moving at a speed of 48 km/h, in how short of a distance can the train be stopped without causing the crates to slide? (constant acceleration.) 2. Relevant equations 3. The attempt at a solution I've worked the entirety of this chapter's problems and this is literally number 5 out of ten dozen. Can someone explain to me how I am supposed to go about this without mass or a normal force? I don't know what to do with just a coefficient of static friction..