Aheavily loaded freight train moves with constant velocity. what is the relationship between the net force on the first car (f1) and the net force on the last car (f2)?

A12-g wad of sticky clay is hurled horizontally at a 100-g wooden block initially at rest on a horizontal surface. the clay sticks to the block. after impact, the block slides 7.5 m before coming to rest. if the coefficient of friction between the block and the surface is 0.65, what was the speed of the clay immediately before the impact?