A wooden joist 15 cm deep by 7.5 cm wide is reinforced by gluing to its lower face a steel strip 7.5 cm wide by 0.3 cm thick. The joist is simply-supported over a span of 3 m and carries a uniformly distributed load of 5000 N. Find the maximum direct stresses in the wood and steel and the maximum shearing stress in the glue. Take Es/Et = 20. (Cambridge)