We blow on hot soup to cool it, and blow on cold hands to warm them — with the very same breath! How can that be?
Blowing gently with an open mouth sends out warm air from inside your body, which can warm cold hands. Blowing hard through pursed lips sends out a fast stream of air that cools hot food by speeding up evaporation.
Why does blowing gently on cold hands with an open mouth warm them up?
Because the air coming from inside your body is warmer than the surrounding air, so it warms your hands
Why does blowing hard on hot soup with pursed lips cool it down?
The fast-moving air speeds up evaporation and carries heat away from the soup's surface, cooling it faster
Many musical instruments, like the flute and the mouth organ, make pleasant sounds when air is blown through them, making the air inside vibrate.
Name one musical instrument that produces sound when you blow air into it.
A flute (other correct answers: mouth organ, bagpipe, or similar wind instruments)
1. Does blowing gently with an open mouth produce warm or cool air on your hand?
2. Does blowing hard through pursed lips make food cooler or warmer?
3. Why does a fast stream of air cool hot food faster than still air?
4. Name one wind instrument that makes sound when you blow into it.
5. Why might someone's glasses fog up when they breathe out on a cold day?