Hot air balloon problem

Hot air balloon

Credit: Brent Myers

A hot air balloon of mass 350 kg is carrying 5 people each of mass 70kg. The total volume of the baloon is 2800m3.

The balloon flies horizontally in dry air 1km above sea level. The atmopheric pressure at this altitude is 89.9kPa and the surrounding temperature is 9ºC. Given that the molar mass of dry air is 28.97g/mol, work out the temperature of the heated air inside the balloon. (You can take gas constant R=8.31J/mol K and you may assume that air behaves as an ideal gas).

General and problem-specific hints are available.

This is one of the problems on, a resource from Cambridge University Engineering Department with more than 200 problems to help you to practice problem solving skills relevant to Engineering. The website also provides general advice such as how to get onto a good Engineering course (whether at Cambridge or elsewhere).

Date posted: 

Monday 12 June 2017