Question

When you heat the air inside a hot air balloon, it rises. Why does this occur?

Answer 1

Here simply....

Hot air balloons fly when the air inside the hot air balloon is less dense than the air surrounding it. Hot air is less dense than cool air; the heated air causes the balloon to rise simply because it is lighter than an equal volume of cold air.

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Answer 2

When we heat the air inside a balloon the air becomes hot. So it also becomes lighter as compared to atmospheric temperature. Therefore by this phenomenon the hot air balloon rises in the air.

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