This problem seemed very straightforward but I've somehow missed something... Three blocks (M1, M2, M3) are in contact with each other on a frictionless, horizontal surface. A horizontal force is applied to M1. If M1= 1.67kg, M2= 2.67kg, M3= 3.78kg, and F= 16.1 N: a) what is the magnitude of the contact force between blocks 1 and 2 b) what is the magnitude of the contact force between blocks 2 and 3 I used the formula P=(M2/M1+M2) x F to find these contact forces, but the answers I got were not correct. for a) I calculated P= (2.67/1.67+2.67) x 16.1 and for b) I calculated P= (3.78/2.67+3.78) x 16.1 This seemed like it should lead to the right answer, but it didn't work. Anyone know what I've done wrong???