A hot air balloon consists of a spherical ball of 14.25 m in diameter. The total mass of the ball, the gondola and passengers is 324 kg. The outside...

A hot air balloon consists of a spherical ball of 14.25 m in diameter. The total mass of the ball, the gondola and passengers is 324 kg. The outside temperature is 13 oC and 102.4 kPa pressure. What temperature should we heat the air in the balloon so that the hot air balloon takes off? Consider that the air is air dry.