Mystery #3Tier 2–3air / forces / density
Why does a huge, heavy hot-air balloon rise into the sky?
A hot-air balloon is enormous and carries people, baskets and heavy gas burners. By rights it should thud to the ground. Instead it drifts upwards. With nothing holding it up and nothing pulling it, what lifts all that weight into the sky?
Your guess
What do you reckon makes the balloon go up instead of falling down?
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