Question: what is the buoyant force acting on the sphere?
Answer: The magnitude of the buoyant force is equal to the the magnitude of the weight wliquid of the displaced liquid. wliquid = ρliquidVg. The volume V of the displaced liquid is the volume of one half sphere, V = 2πr3/3 = 2π(6cm)3/3 = 452cm3.