An 6.40kg block rests on a 12.5kg block. The interface between the lower mass and the table is frictionless, but there is friction (static friction μs and kinetic friction μk) between the two blocks. A horizontal force F acts on the upper block and causes both blocks to accelerate. The acceleration of both blocks when they begin to slip is 2.0 m/s2. fk=μkFN fs=μsFN I guess I have no idea how to start with this question. Am I supposed to find the normal force first and work from there? Where do I even go from there? Any help would be appreciated, thanks much!