1. The problem statement, all variables and given/known data http://s76.photobucket.com/albums/j29/E_man777/?action=view¤t=NewBitmapImage.jpg Consider three versions of a problem with three blocks of masses m, 4m, and 3m. The small mass is always on top of the large mass, and the 3m mass is accelerating downwards (but at different rates). There is friction between the m and 4m block but not anywhere else. The coefficients of kinetic and static friction are 0.6 and 0.9 respectively. Pulleys and strings are massless. a) Draw the forces of friction in each case. Which are static and which are kinetic? b) In which case is the acceleration the greatest?... the least? Justify your choice. c) Determine the accelerations in each case and check your answer to (b). 2. Relevant equations sum of F = ma. Fr = uN 3. The attempt at a solution So in each of the cases the friction must be kinetic? Please help.