May I suggest that this thread be limited to "ideal tides" while
the parallel "double tide cause" thread continues discussing
more realistic tide (influenced also by the earth fast rotation,
by continental shapes and other local peculiarities). In physics
we deal with ideal tides and good understanding of them
would be useful to many of us. A teacher who understands
Newtonian tides well will be in a good position to start
dealing with real tides.
In that spirit let me suggest the following simulation; I wish
I had time to perform it. Consider a perfectly spherical earth
at rest in the absolute Newtonian space; it is anchored to it
like in IP; Interactive Physics is a simulation program. There
is a frictionless track along the equator supporting 3600 cars
which are connected with identical springs. Cars are at the
same distance from each other (initial static equilibrium).
Then an "asteroid or moon" is anchored, it is located in the
same plane as the rail track. The mass of that object is
variable. We begin with a very small mass and nothing
happens on earth. But for a large mass the chain of cars
will start readjusting; the cars will no longer be equidistant.
What will be the new distribution of cars?
I suspect (yes, it is only a hinge) that a new equilibrium
will display one bulge and one anti-bulge. In this context
the term "bulge" is used to indicate a region (closer to the
"moon") in which the concentration of cars has a maximum
while the term anti-bulge indicates the minimum (farther
away from the "moon").
I am not sure that by answering this question we can
understand tides better. So let me suggest a better simulation.
Remove the anchors and allow orbiting. First without spinning
then with slow spinning (slow with respect to "response and
damping" time constants of the chain). Is there going to be
two bulges or only one? Would the two bulges be identical?
Ludwik Kowalski