A sphere 1 m in diameter floats half submerged in a tank of oil( Sg = 0.80). a.) What is the upward force acting on the sphere? b.) What is the minimum weight of an anchor w/ a density of 20,000 N/m^3 that will be required to submerge the sphere completely? c.) What minimum weight of a body placed on the top of the sphere will be required to just submerge sphere completely?