How To Suck An Egg Into A Bottle

Step 1: You will need

Step 2: Method

Crack open your hard boiled egg and remove the shell. Place it in the neck of a milk bottle, (Jack is using a conical flask) to see that it won't sink inside.
Light a piece of paper and carefully place it in the bottle. Then quickly pop the egg back in the neck of the bottle and watch what happens. The egg will be sucked into the bottle and remain fully intact.
Tip the bottle upside down and watch how the egg does not want to come out again.
Very carefully remove any big bits of paper from the bottle and blow into the neck. The egg will slip out into your hand.

Step 3: Conclusion

Why did this happen? The air in the atmosphere exerts "atmospheric pressure". When the paper was lit, the air inside the bottle got hotter and expanded. Some of the air escaped from the bottle. When the flame went out, the air inside the bottle cooled down and contracted so the air pressure decreased considerably. This meant the atmospheric pressure outside the bottle was greater than that inside the bottle. This pushed the egg into the bottle. When you blew into the bottle, the air pressure inside grew so that is was relatively greater than the atmospheric pressure outside, and forced the egg out of the bottle again.