The post is made of Douglas fir and has a diameter of
60 mm. If it is subjected to the load of 20 kN and the soil
provides a frictional resistance that is uniformly distributed
along its sides of w = 4 kN>m , determine the force F at its
bottom needed for equilibrium. Also, what is the displacement
of the top of the post A with respect to its bottom B? Neglect
the weight of the post.