3. Hot air balloons float in the air because of the difference in density between cold and hot air. Consider a balloon in which the mass of the pilot basket together with the mass of the balloon fabric and other equipment is mp. The volume of the hot air inside the balloon is V, and the volume of the basket, fabric, and other equipment is V2. The absolute temperature of the cold air outside the balloon is To and its density is Pc. The absolute temperature of the hot air at the bottom of the balloon is Th (where Th>To). The balloon is open at the bottom, so that the pressure inside and outside the balloon is the same. Assume that we can treat air as an ideal gas. Use g for the magnitude of the acceleration due to gravity. For the balloon to float, what is the minimum temperature Tmin of the hot air inside it in terms of the variables given?