Caution: make sure you ask a parent or guardian
for help!
What you need:
- Glass milk bottle or conical flask
- Hard boiled egg
- Small piece of newspaper
- Lighter or matches
What to do:
Peel your hard boiled egg and make sure all the shell is
removed.
Place the egg in the neck of the milk bottle, to check that the
egg will sit neatly in the top of the milk bottle and that it won't
slip through.
Remove the egg.
Ask your parent or guardian to light the piece of newspaper and
carefully place it inside the milk bottle.
Quickly put the egg back on the neck of the bottle and watch
what happens.
Did you see the egg get sucked into the bottle?
If you tip the bottle upside down the egg will remain inside: it
is trapped.
Carefully remove any bits of paper from the top of the milk
bottle and tip it up. Blow gently into the neck of the bottle and
the egg should fall out. Amazing!
Check out this video to see the experiment in action:
Or watch on VideoJug
Why does it happen?
When the paper was lit, the air inside the bottle got hotter and
expanded. The hot air had nowhere to go as the egg blocked the
entrance to the milk bottle. When the flame went out, the air
inside the bottle cooled down and contracted. This caused the
pressure inside the bottle to decrease, making it lower than the
air pressure outside the bottle. This higher pressure outside the
bottle pushed the egg into the bottle.
When you blew into the milk bottle this increased the pressure
inside the milk bottle so that it was greater than the air pressure
outside the bottle. This pushes the egg out of the bottle. Very
clever!