1. The problem statement, all variables and given/known data Three blocks in contact with each other are pushed across a rough horizontal surface by a 75 N force as shown. The acceleration of gravity is 9.8 m/s2 . [PLAIN]http://img178.imageshack.us/img178/6198/007ow.png [Broken] If the coefficient of kinetic friction between each of the blocks and the surface is 0.076, find the magnitude of the force exerted on the 3.5 kg block by the 4.1 kg block. Answer in units of N. 2. Relevant equations sum of Fy=N-mg=0 => N=mg sum of Fx= -fk=max fk=uN 3. The attempt at a solution I have no clue how to figure out the force just between those two block... Do I add the first two blocks together to act a one force against the third block?