Friday, December 5, 2008




Raw Egg or Boiled video.

Mineral Identification. This video covers luster, hardness,
cleavage/fracture, streak, and other tests.

Mineral ID Chart for use with the Mineral Identification video.

How can you tell if an egg is raw or cooked without cracking the shell? There are several ways? (How many can you find?) This is one of my favorites. You will need:

- a raw egg

- a hard boiled egg

- a smooth, flat surface

- a pencil

- a small bowl

Place both eggs on the table and mix them around until you are not sure which is which. Select one and place it on the flat surface. Give it a good, hard spin and watch carefully. Notice how quickly it spins. Then test the other egg the same way.

You will find that one egg spins very quickly, while the other egg spins much slower. Use the pencil to write “A” on the egg that spun quickly, and “B” on the egg that spun slowly.

Take egg A and spin it again. Once it is spinning, use your fingers to stop the egg and then quickly release it again. You only want to touch it long enough to get it to stop for an instant. Notice that when you remove your fingers, the egg pretty much stays still.

Do the same thing with egg B. This time you will find that when you remove your fingers, the egg starts spinning again.

Egg A is the hard boiled egg, and egg B is the raw egg. How do I know? The hard boiled egg is solid all the way through. When you spin the shell, the entire egg spins. When you stop the shell, the whole thing stops.

On the other hand, the inside of the raw egg is liquid. Crack egg B into a small bowl. Ahhh! It really is the raw egg. We are going to pretend that the bowl is the shell of the egg. Gently spin the bowl on the table. Notice that when it first starts to spin, the egg lags behind. Its inertia keeps it still until the friction between the bowl and the egg is enough to get the egg spinning. That is why the raw egg spun slower. The inertia of the liquid inside was slowing it down.

Spin the bowl again, and this time stop it quickly. When the bowl stops, the egg keeps spinning. Again, its inertia keeps it moving until friction with the bowl slows it down. That is what causes the raw egg to start spinning again when you release it. You stopped the shell, but the liquid inside was still spinning.

The last thing to do is to clean up and get rid of the eggs. I scrambled the raw egg, chopped the boiled egg, sliced some green olives, and used some mayonnaise to make myself and egg and olive sandwich. Yum! Ahh, the fun of science!


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