Two blocks are sliding to the right across a horizontal surface, as the drawing shows. In Case A the mass of each block is 3.0 kg. In Case B the mass of block 1 (the block behind) is 6.0 kg, and the mass of block 2 is 3.0 kg. No frictional force acts on block 1 in either Case A or Case B. However, a kinetic frictional force of 5.8 N does act on block 2 in both cases and opposes the motion. For both Case A and Case B determine (a) the magnitude of the forces with which the blocks push against each other and (b) the magnitude of the acceleration of the blocks. I'm in intro physics...I've been looking at this problem for a while. I understand that I am supposed to set up a free body diagram for both boxes. Let's just look at part A first. This is my reasoning. The two boxes are contiguous and thus accelerate at the same magnitude. On box 1 there is a normal force and mg working on it. Then I THINK there is a force pointing to the left. Let's call this force F. I THINK force F is caused by the equal and opposite reaction of pressing it pressing on block B. Is my logic correct? If this is true, then for block 1: -F=ma Then on Block B, we have friction working on it towards the left and the force F put on it. This is in the +x direction. We also have normal force and weight. And for block B: F - Ffriction = ma????