Q10.23Long answer
A hot air balloon is a sphere of radius 8 m. The air inside is at a temperature of 60°C. How large a mass can the balloon lift when the outside temperature is 20°C? (Assume air is an ideal gas, R = 8.314 J mole–1K-1, 1 atm. = 1.013×105 Pa; the membrane tension is 5 N m–1.)