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 = 12.2 n , the contact force between the boxes is 8.90 n ; if, instead, box 2 is pushed with the force f, the contact force is 3.30 n . in either case, the boxes move together with an acceleration of 1.50 m/s2. what is the mass of box 1? what is the mass of box 2?

Aperson gives a shopping cart an initial push along a horizontal floor to get it moving, and then lets go. the cart travels forward along the floor, gradually slowing as it moves. consider the horizontal force(s) on the cart while it is moving forward and slowing. which of the following statements is correct? (a) both a forward and a backward force are acting on the cart, but the forward force is larger. (b) only a forward force is acting which diminishes with time. (c) both a forward and a backward force are acting on the cart, but the backward force is larger. (d) only a backward force is acting, no forward force.