1. The problem statement, all variables and given/known data A good estimate for the volume of a particular hot air balloon is 2800 m3. Suppose the total load (passengers, fuel, balloon fabric, etc.) on a hot air balloon is 724 kg. In preparing to launch, the pilot heats the air inside to an average temperature of 210 oC, giving it a density of 0.95 kg/m3 (compared to a density of 1.2 kg/m3 for the air outside the balloon). [Note! This means that the total mass of the hot air balloon is 724 kg plus the mass of the hot air in the balloon!] How much extra mass does the pilot need to keep in the basket in order to stay on the ground while all passengers are on board? 2. Relevant equations 3. The attempt at a solution I'm really lost here. Any help would be great.