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At 22:52 9/6/01 +0300, you wrote:
One of my students in the sixth grade science class asked the following
question;
"Is it true that the earth creates a big noise while it is rotating? Why
cant we hear it? Why is there such a sound?"
I don't have a clear answer for these questions. Can anyone help?
Many thanks.
Muhsin Ogretme
Science/Physics Teacher
Muhsin, you have probably been following the interesting debate about
ocean tides, and the prolate shape the ocean surfaces would adopt,
if not for the many complicating factors which exist.
You will have read that not only do the gravity and spin and rotation
gradients affect the water, but also the Earth itself.
It is a short step from here to ask, can I actually hear a circadian
rhythm and its second harmonic?
This seems like the kind of adventurous earth physics experiment that
might appeal to young students: the concept is easy to grasp:
if I place a microphone in intimate contact with a deep rock formation
perhaps in a quiet mine, can I capture evidence of an earth tide?
A first step might be a tape recorder setup with a low noise pre amplifier
perhaps. You might well find that the slow grinding of the Earth flex
is not perceptible by this means.
But the next step is to collect a sound sample over a period of many days.
One would not need to sample very frequently, perhaps three times an hour.
There are college physicists who I am sure would help with analyzing
this sort of time series - a fourier analysis of 1024 such samples over a
two week period might be gratifying, to start with.
There is a possibility for a library search for prior work in this area.
Is this a project which might be of interest to your students? Would you
need help with equipment? Where are you located?
Brian W
brian whatcott <inet@intellisys.net> Altus OK
Eureka!