In class we showed that hot air at atmospheric pressure is lessdense than cooler air at the same pressure.
Because of this difference hot-air balloons can stay aloft.Assume that you have an air-balloon that has
the volume of 500 m3 and the surrounding air is at 100C. Youwant to lift 250 kg object (in addition to
the mass of the hot air that is inside the balloon). What mustbe the temperature of the air in the balloon?
03
The density of air at 10 C and atmospheric pressure is 1.23 kg/m .The heated air inside the balloon is at
roughly the same pressure as the outside air.
