A father (weight W = 830 N) and his daughter (weight W = 340 N) are spending the day at the lake. They are each sitting on a beach ball that is just submerged beneath the water (see the figure). Concepts: (i) Each ball is in equilibrium, being stationary and having no acceleration. Thus, the net force acting on each ball is zero. What balances the downward-acting weight in each case? (ii) In which case is the buoyant force greater? (iii) In this situation, what determines the magnitude of the buoyant force? (iv) Which beach ball has the larger radius? Calculations: Ignoring the weight of the air in each ball, and the volumes of their legs that are under the water, find the radius of each ball.