# Another balloon problem

1. May 8, 2004

### dubsinpubs

If the volume of a balloon is V=416m^3 and the surrounding air is T=13.8 C. The temperature of the air in the balloon is 213 C. What is the max amount of mass, in addition to the mass of the hot air, the balloon can lift? Density of air is of air outside balloon is 1.22 Kg/m^3.

I know I need to use the Ideal Gas Law PV=nRT. Also the pressure exerted on the balloon by the air in the balloon is = to the pressure by the air outside of the balloon. I know to convert C to Kelvin. The only thing related to mass in this prob is density. I am just stuck on where to go w/ this. Any help would be appreciated :)

2. May 9, 2004

### Gokul43201

Staff Emeritus
What is the condition that needs to be satisfied for something to float ?

What is the mass of the hot air in the balloon ? Can this not be calculated using the Gas Law, assuming air is 80% N2 and 20% O2, and the pressure is close to 1 atm (by the argument you used) ?

Think about the first question and take it from there...