Question

A hot air balloon has a volume of 65,00 cubic feet of hot air. The balloon is at sea level on a standard day. If the temperature of the hot air in the balloon is 1100F, determine the lifting force of the balloon.

Answer 1

If you heat that air by 100 degrees F, it weighs about 7 grams less. Therefore, each cubic foot of air contained in a hot air balloon can lift about 7 grams. That's not much, and this is why hot air balloons are so huge -- to lift 1,000 pounds, you need about 65,000 cubic feet of hot air.