This Week's Experiment - #263 Jurassic Vibrations
I got the idea for this week's experiment while rewatching the Jurassic Park
trilogy. If you have seen the movies, you probably remember that as the T.
rex approached, they could see the vibrations in a glass of water. That got
me to thinking that maybe you could use the water to see the vibrations of
smaller monsters, such as little brothers. For this experiment, you will
need:
a glass or bowl of water
a bright flashlight
a darkened room
a stack of books, a little taller than the container of water
something to use for propping up the flashlight
Place the bowl of water on the table. Put the stack of books about a foot
away. Lay the flashlight on the books, so that it is pointing towards the
water. Lift the back end of the flashlight and prop it up. You need to tilt
the flashlight so that the beam of light hits the surface of the water. Now
you are ready to begin.
Switch the flashlight on, lower the lights and look around. You should see a
spot of light on the wall or ceiling caused by the beam of the flashlight
reflecting off the water. Watch this spot carefully as you stomp your foot.
What happened? The light wavered and rippled. Your foot caused the floor to
vibrate, which caused the table to vibrate, which caused the glass of water
to vibrate. The surface of the water rippled as it vibrated, and this showed
up in the reflection of the flashlight.
Now that you know what to look for, try making smaller vibrations. Tap your
foot. Have someone walk by. Wait for a truck to drive past. Drop a coin on
the table. How small a vibration can you detect? That will depend on the
construction of your table, the brightness of the light, what kind of floor
you have, and even how your house is built. Try putting the device in
different rooms. If you use the same table, same bowl, etc., you should be
able to test to see which floor carries the most vibration. You could also
test different tables, to see whether a sturdy table transmits vibrations as
well as a wobbly one. You might try to see how far away you can detect a
stomp, and you may be surprised at how far it is. You could try using
different containers for the water. Does a stemmed wine glass work the same
as a bowl? Is a shallow saucer any better than a deep container? I warn you
that I started playing with this and used up an entire evening. Be careful
or you might get hooked and wind up as a structural engineer.
From Robert Krampf's Science Education Company
PO Box 60982
Jacksonville, FL 32236-0982
904-388-6381
krampf@aol.com
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