Why do hot air balloons float?
Show answer & explanation
Answer: Hot air is lighter than cold
Hot air is lighter than cold ✓ — Correct! Heating air makes molecules move faster and spread apart, reducing density. The hot air inside weighs less than the cold air outside, creating buoyancy. The balloon rises like a bubble in water!
The balloon pushes air down — Wrong. Balloons don't push air for thrust. They float because hot air is less dense than surrounding cold air.
Flame creates upward thrust — Wrong. The flame heats air, it doesn't create thrust. Buoyancy from density difference provides lift.
More Transportation questions
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