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Re: Coriolis

I would like to thank John for correcting me (see below). And
for helping me in private. I did not know that in Interactive
Physics two overlapping objects can now be selected and
ordered not to collide with each other. The "do not collide"
command is in the OBJECT menu.

Here is what I was able to improvise in minutes. With gravity
turned off I created a small platform centered at x=0, y=0 and
rotating at 3 degrees per second. A canon ball, initially at
x=0, y=0 had the initial velocity of 0.05 m/s along the y axis.
Nothing spectacular in the absolute frame, only a tracked
trajectory along the y axis, at constant speed.

Then another frame of reference was attached to my platform
(it must first be selected; the command is in the VIEW menu).
I run the program again but this time it showed the same
trajectory as seen from the rotating frame. It was a spiral
curve. And the speed was increasing (distances between
tracks became larger and larger). Centripetal acceleration
is responsible for changes in speed, coriolis accelerations
for changes in directions.

I suppose that numerous measurements can be made but I
was not interested. A simulation like this can be probably
useful in the context of teaching a course mechanics. But
it is not a substitute for what one would experience on a
real mary-go-round platform without horses (3-dim and
gravity can not be turned off). Perhaps amusement park
operators can be persuaded to remove horses and affer
some learning experience for kids on physics days. The
senior citizen status would not prevent from trying to
walk, and to play ping-pong, on a slowly rotating
platform.
Ludwik Kowalski

John Mallinckrodt wrote:

On Mon, 9 Aug 1999, Ludwik Kowalski wrote:

I just tried to simulate the Coriolis effect with Interactive
Physics and came to a conclusion that this is not possible
in its two-dimensional universe. Am I correct?

No. In fact possibly my favorite use of IP is in displaying the
effects of rotating reference frames. See my IP page at

http://www.csupomona.edu/~ajm/myweb/index.ip.html

for some examples.

In the case you are concerned with, all you have to do is create a
rotating object, select it and create a "New Reference Frame" that is
lnked to it. Thereafter, the motion of all objects will show the effects
of both the coriolis and the centrifugal forces.