Two blocks rest on a horizontal frictionless surface. (top block weighs xkg, the bottom box weighs 10kg). The surface between the top and bottom blocks is roughened so that there is no slipping between the two blocks. A 40N force is applied to the bottom block and the two blocks are found to be moving together with an acceleration a=2m/s^s
(a) what is the mass of the top box?
(b) what is the force of static friction between top and bottom blocks
(c) what is the minimum coefficient of static friction necessary to keep the tip block from slipping on the bottom block.