1. The problem statement, all variables and given/known data An emtpy rubber balloon has a mass of 0.0120 kg. The balloon is filled with helium at 0 degrees Celcius, 1 atm pressure, and a density of 0.179 kg / m3. The filled balloon has a radius of 0.500 m. A. What is the magnitude of the buoyant force acting on the balloon? B. What is the magnitude of the net force acting on the balloon? 2. Relevant equations Density of air = 1.29 kg/m3 Density of helium = 0.179 kg/m3 Net force = 0 = ((density of fluid x volume of fluid) - (density of object x volume of object))(9.81 m / s2) Net force = Buoyant force - Weight of object 3. The attempt at a solution I don't know what equation to use to find either force or what to do to get started.