Hot air balloon rises up in the air because:
A hydrogen balloon rises in air because
Hot air always rises up.
Ventilators are provided near ceilings in the rooms of our houses because:
1. Hot air is lighter than cool air.
2. Hot air rises up and cool air settles down.
3. Hot air is heavier than cool air.
How do hot air balloons rise up in the air? [3 marks]
(a) Why does hot air rise up?
(b) How does a hot-air balloon work? [3 MARKS]