In fig. 12-67a, a uniform 40.0 kg beam is centered over two rollers. vertical lines across the beam mark off equal lengths. two of the lines are centered over the rollers; a 10.0 kg package of tamales is centered over roller b. what are the magnitudes of the forces on the beam from (a) roller a and (b) roller b? the beam is then rolled to the left until the right-hand end is centered over roller b (fig. 12-67b). what now are the magnitudes of the forces on the beam from (c) roller a and (d) roller b? next, the beam is rolled to the right. assume that it has a length of 0.800 m. (e) what horizontal distance between the package and roller b puts the beam on the verge of losing contact with roller a?