Tide Experiment

Tide Experiment

This experiment will explain why there is a bulge on the side of the Earth that is opposite of the moon.

Ask your teacher or parent for permission before doing this experiment.

What you will need for this experiment is: a piece of string (about 2 feet long), a paper cup, a hole puncher, and water.

Take the cup and punch a hole on either side of the cup near the top of the cup. The holes should be across from each other.

Tie each end of the string to the cup using the holes that you just made. Now you have a handle for you cup.

Add a little water to the cup. You do not want a lot.

Go to the sink, and turn the cup upside down. The water should pour out into the sink.

Put a little more water into the cup. This time, holding the handle, swing the cup around in a circle so that it goes over your head. Notice that the water does not pour out of the cup.

Explanation

When the cup was hanging near the ground, the water was sitting in the bottom of the cup. Here, the Earth's gravity is pulling down on the water keeping it in the bottom of the cup. This is like the water that is closest to the moon. The moon is pulling on that water making it bulge out towards it.
When the cup is swung in a circle, and is upside down, the water is still in the bottom of the cup. We expect for the water to fall out because of the gravity pulling down on it. But it doesn't. This is like the other side of the Earth where there is a bulge. You learned that the moon moves around the Earth. For the same reason the water did not fall out of the cup, there is a bulge on the opposite side of the Earth. Because of the circles that both the Earth and the cup are going in, there is a second pull that is opposite of the moon (or gravity) that creates the second bulge (or keeps that water in the cup).

NOTE: We understand that this concept is hard to understand. If you still are unclear and want to find out more, you can go to this site and submit a question to be answered.

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The Tides page.