From: Ben Pittenger (benpittenger@earthlink.net)
Date: Mon Sep 16 2002 - 07:37:29 PDT
Date: Mon, 16 Sep 2002 07:37:29 -0700 From: "Ben Pittenger"<benpittenger@earthlink.net> Subject: Moon Exercises - orbits Message-ID: <Springmail.0994.1032187049.0.26342600@webmail.pas.earthlink.net>
I think the effects of the moons on the motion of their respective planets is
often overlooked. One exercise to model these effects is to have a series of
masses on strings/ropes for the students to spin over their heads (outside, of
course, with due attention to safety - if you are really concerned, students
can observe from behind a baseball backstop). The masses should range from
quite small to quite large.
As the mass gets larger, the motion of the person spinning the mass
necessarily increases. Even the smaller masses require some motion of the
hand, in a small circle, but the students don't often notice this until
they've seen the larger motion when they spin a larger mass. Even then, it is
often the observing students who see the motion, more than the student who is
spinning the object.
As the mass gets larger and larger it becomes more and more apparent that each
mass is affecting the other - not just the moon orbiting around an
unresponsive planet.
(I suppose if you are careful, you could show the students some good square
dance techniques of spinning with each other, then have pairs of students
demonstrate for the class. (These techniques are fun - I was always surprised
how fast it feels like you are going.) The first pair could be a large
student and a small student and you could end with students of approximately
the same mass spinning each other.)
Ben
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