(1.51) A solar panel is to be mounted at the top of a cylindrical post that is rigidly attached to the ground at its bottom, and that is protected from extreme bending by four guy wires strung from the top of the post to the ground. The post will be made of recycled polyethylene terephthalate (PET), which has an elastic modulus of approximately 3.5 GPa and a Poisson's ratio of 0.43. If the solar panel weighs 14.8 kg and the post must be 8 m tall to lift the panel above surrounding obstacles, what is the minimum post radius needed to avoid failure by buckling? Is this post diameter actually likely to be a safe design choice? Based only on the required post radius, what is your opinion about the choice of PET for this application?