A He-filled balloon is tied to the 2 m long 0.05 kg uniform string. The balloon is spherical having radius 0.40 m. If released, the balloon lifts a length h of string and then remains in the equilibrium. Find h. The balloon envelope consists of mass 0.25 kg. (Density of He = 0.179 kg/m3 and air 1.29 kg/m3)