Two boxes are at rest on a smooth, horizontal surface. The boxes are in contact with one another. If box 1 is pushed with a force of magnitude
F = 11.6 N , the contact force between the boxes is 8.60 N ; if, instead, box 2 is pushed with the force F, the contact force is 3.00 N . In either case, the boxes move together with an acceleration of 1.65 m/s2 .