Question

Challenge problem. (extra credit) Consider a hot-air balloon. The deflated balloon, gondola, and two passengers have a combined mass of 315 kg. When inflated, the balloon contains 912 m3 of hot air. Find the temperature (?C) of the hot air required to lift the balloon off the ground. The air outside the balloon has a temperature of 20.2?C and a pressure of 0.916 × 10^5 Pa. The pressure of the hot air inside the balloon is the same as the pressure of the air outside the balloon. The molar mass of air is 29 g/mol. Hint: First find the density of the air outside the balloon. Then use Archimedes’ principle to find the density required for the air inside the balloon. Then find the temperature of the air inside the balloon.

Answer #1

The mass of a hot-air balloon and its cargo (not including the
air inside) is 220 kg. The air outside is at 10.0°C and 101 kPa.
The volume of the balloon is 550 m3. To what temperature must the
air in the balloon be warmed before the balloon will lift off? (Air
density at 10.0°C is 1.244 kg/m3.)

A hot air balloon is operated with the inside
temperature of 125oF when the outside temperature is
52oF. What must be the minimum volume of this balloon to
carry a 300-kg load (including its own mass)? The atmospheric
pressure is 1.013×105 Pa and the molecular mass of air
is 29 atomic mass units.

1. A hot-air balloon, open at one end, rises when the air inside
is heated by a flame. How does the temperature, pressure and
density of the air inside the balloon compare to the air outside?
For each property, state if they are higher, lower or the same
inside the balloon versus outside.
2. What is the atomic mass of Aluminum (Al)? Give your answer in
both atomic mass units and in kilograms. Mass = _____________ u
(atomic mass units)...

A hot air balloon has a mass of 250 kg and carries two
passengers whose average weight is 84 Kg. The balloon, which has a
diameter of 12 m, rises through atmospheric air which is at 20oC.
Find the total buoyant force on the balloon. Atmospheric pressure
is 100 kPa with gas constant = 8.13 kJ/kmol.K and molar mass of the
air is 28.97 g/mol

The envelope and basket of a hot-air balloon have a combined
weight of 2.36 kN, and the envelope has a capacity (volume) of 2.29
x 103 m3. When it is fully inflated, what
should be the temperature of the enclosed air to give the balloon a
lifting capacity (force) of 2.64 kN (in addition to the
balloon's weight)? Assume that the surrounding air, at 20.0°C, has
a weight per unit volume of 11.9 N/m3 and a molecular
mass of 0.0280...

1) A hot air balloon consists of a very large bag filled with
heated air at 120.0 °C produced from a propane burner. It has a
basket hanging under it in which several people can ride. The
average hot air balloon has a volume of 2.80 × 103 m3 when fully
inflated.
a) Determine the work (in kJ) needed to inflate the balloon under
an external air pressure of 1.00 atm.
b) The specific heat of the air found in...

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