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
- Why can one runway crash cripple a whole airport?
- Why isn't a go-around always possible at the last moment?
- Why doesn't a radioed 'Stop!' mean instant braking?
- Why can one runway emergency make a second mistake more likely?
- Why do runway crashes often come from several small failures at once?
- Why doesn't a jet's anti-collision system simply stop a runway crash?