1. The problem statement, all variables and given/known data The coefficient of static friction is 0.625 between the two blocks shown. The coefficient of kinetic friction between the lower block and the floor is 0.137. Force F causes both blocks to cross a distance of 4.46m, starting from rest. What is the least amount of time in which the motion can be completed without the top block sliding on the lower block, if the mass of the lower block is 1.57kg and the mass of the upper block is 2.48kg? and also, a similar question: A pickup truck is loaded with crates of oranges. The crates have a co-efficient of static friction of 0.234 with the floor of the truck. When the truck is traveling at a speed of 46.2km/hr, in how short a distance can it come to rest without causing the crates to slide? 2. Relevant equations Kinematic equations: d=vit+(at^2)/2 F-Fk=ma Fk=μ/kN Fs=μsN 3. The attempt at a solution Fmax=μkN Fmax=(0.625)(2.48)(9.81) Fmax=15.2055 N F-Fk=ma 15.2055-(9.81)(0.137)(1.57+2.48)=(2.48+1.57)a a=2.4105 m/s^2 4.46=(0)t+((2.4105)t^2)/2 t=1.56 s This answer is wrong, but I'm not sure what I did incorrectly. The second question I have no idea what to do, since no masses are given, only the value of the coefficient of static friction. I tried equation F=ma and F=[μ][/s]mg, but cancelling the masses didn't make sense to me.