Help with a problem: A spherical, hydrogen-filled balloon has a radius of 12 m. The mass of the balloon plastic and support cables is 196 kg. What is the mass of the maximum load the balloon can carry? (Density of hydrogen = 0.09 kg/m^3; density of air = 1.25 kg/m^3) I do not know where the radius of the balloon ties in but this is what I have so far. V = mass/density = (196 kg)/(0.09 kg/m^3) = 2.2 x 10^3 m^3 mass of displaced air = (2.2 x 10^3 m^3) x (1.25 kg/m^3) = 2.9 x 10^3 kg weight of displaced air = (2.9 x 10 ^3 kg) x (9.8 m/s^2) = 28420 N maximum load the balloon can carry = (28420 N) / (9.8 m/s^2) = 2900 kg Is that about right, or do I need to include the area? If I need to include the area of the balloon, how do I do that?