Chapter 11, Problem 11.12E

A uniform aluminum beam 9.00 m long, weighing 300 N, rests symmetrically on two supports 5.00 m apart (Fig. E11.12). A boy weighing 600 N starts at point A and walks toward the right. (a) In the same diagram construct two graphs showing the upward forces F_A and F_B exerted on the beam at points A and B, as functions of the coordinate x of the boy. Let 1 cm = 100 N vertically, and 1 cm = 1.00 m horizontally, (b) From your diagram, how far beyond point B can the boy walk before the beam lips? (c) How far from the right end of the beam should support B be placed so that the boy can walk just to the end of the beam without causing to tip?

Figure E11.12