8. A spherical balloon is 40 ft in diameter and surrounded by air at 60°F and 29.92 in Hg abs. (a) If the balloon is filled with hydrogen at a temperature of 70°F and atmospheric pressure, what total...

Extracted text: 8. A spherical balloon is 40 ft in diameter and surrounded by air at 60°F and 29.92 in Hg abs. (a) If the balloon is filled with hydrogen at a temperature of 70°F and atmospheric pressure, what total load can it lift? (b) If it contains helium instead of hydrogen, other conditions remaining the same, what load can it lift? (c) Helium is nearly twice as heavy as hydrogen. Does it have half the lifting force? R for hydrogen is 766.54 and for helium is 386.04 ft.lb/lb.°R. Ans. (a) 2381 lb; (b) 2209 lb