EGG-IN-A-BOTTLE  more experiments

ADULT SUPERVISION REQUIRED!

Materials:

hardboiled egg (medium seems to work best) (tip: a water balloon the size of a small egg will work just as well)

bottle with opening slightly smaller than egg (glass specialty tea bottles work well, as do most juice bottles and some sports drink bottles)

paper strip

lighter or matches

cooking oil or shortening (or similar)

Directions:  Remove the shell from the egg.  Use the oil or shortening to make the opening of the bottle slippery.  Cut a strip of paper about 1/2" wide.  The strip should be a little shorter than the height of your bottle.  Fold the strip in half so there is a crease.  Now you are ready!  Light the strip of paper on fire and count to 3 -- the strip should be really burning.  Now drop it fire end into the bottle and quickly set the egg, fat side down, on top of the opening.  Smoke will fill the bottle, the egg will hop and pop, then get sucked down into the bottle!

If it doesn't work for you the first time, don't worry!  It took us 5 tries before we figured out the right way to do it.  Our mistakes were:

• Bottle opening was too small/egg too big.  Solution:  use medium instead of large eggs.

• Not enough fire in the bottle because the flame went out too soon.  Solution:  let the paper really catch fire by counting to 3 first.  The paper should have a substantial flame when you first drop it in. If it goes out right away, the experiment probably won't work.

• Bottle was too big.  We tried a large juice bottle that collapsed inward as the air pressure inside the bottle decreased.  The egg sat there for the longest time -- then all of a sudden was sucked inside.  It was dramatic -- but not at all what we planned!

• Bottle was too weak.  When the bottle collapses inward it takes away from the effect of the egg being sucked in.  Solution:  use a sturdy bottle, such as heavy plastic or glass.

Science:  The burning piece of paper heats up the air molecules in the bottle, making the air expand.  That's great if the air can get out, but when there is an egg in the way, the air can't escape.  It tries at first, which is what causes the egg to jump around.  But then, just as the hot air is making its escape, the flame runs out of oxygen and burns out.  When this happens, the air cools again and contracts. Now the air starts to move the opposite direction, because with the air contracting, there is more room inside the bottle than there is air (a partial vacuum), so all of a sudden the air on the outside is trying to push itself in!  Voila, the egg that is in the way gets pushed in too! 

Weird Fact:  Did you know that all of the parts of an egg are edible -- even the shell?  It might not taste very good, but shells are made mostly of calcium carbonate, which is safe for humans to eat.