Consider a man whose weight is w = 212 lb. Find the minimum radius (m) of a helium balloon that will lift him off the ground. The density of helium gas is 0.178 kg/m3 , and the density of air is 1.29 kg/m3.
(a) Neglect the weight of the deflated balloon itself. Assume that the shape of the balloon is a sphere. Neglect the buoyant force of the air on the man.
(b) If we replace the helium with hydrogen gas, how much more weight (lb) can the balloon lift? The density of hydrogen gas is 0.089 kg/m3. Find how much weight in excess of w the same balloon inflated to the same volume can lift.