How do hot air balloons stay in the air?

Answer 1

It is really quite simple and is based on the principle that hot air rises, you will have experienced the warmer air at the kitchen ceiling when cooking if you have to change a light bulb. The balloon or envelope is filled with hot air causing it to lift off. This has to be large, for example to lift 1000 pounds of weight requires 65,000 cubic feet of air and that is big! We need to keep the Hot Air Balloon up so we have to keep replacing this with hot air as it cools; this is done with the burner which we can relate to being the engine.