A wooden beam is trapezoidal in section, 400 mm deep, the horizontal parallel sides being 300 mm and 100 mm. Find the moment capacity of this section if the permissible stresses are 14 N/mm2 in...

A wooden beam is trapezoidal in section, 400 mm deep, the horizontal parallel sides being 300 mm and 100 mm. Find the moment capacity of this section if the permissible stresses are 14 N/mm2 in compression (top fibre) and 10 N/mm2 in tension (bottom fibre).