A timber beam AB of length L and rectangular cross section carries a single concentrated load P at its midpoint C. (a) Show that the ratio a, of the maximum

values of the shearing and normal stresses in the beam is equal to 2h L, where h and L are, respectively, the depth and the length of the beam. (b) Determine the depth h and the width b of the beam. knowing that L 2 m .P 40 kN, 960 kPa. 0= 12 mpa