Re: About absolute reference frame......


Mike wrote:
PD wrote:
Mike wrote:
Tom Roberts wrote:
Mike wrote:
Tom Roberts wrote:
Newton's second law is F=ma, and in a rotating frame that
simply does not hold -- one must _invent_ fictitious "forces" (called
"centrifugal force" and "Coriolis force") in order to "save" the law.

These forces are not ficticious at all. This name is a historical
misnomer.

Applying the word "force" to them is the misnomer, not the word
"fictitious".


Are you trying to deny the real existence of centrifugla
forces that make centrifuges work and coriolis forces who are
responsible for the rotation of the water when it goes down the drain?

But they don't. <shrug>

Centrifuges work because the material in them tries to move in a
straight line (relative to the inertial frame of the centrifuge's
center), but the centripetal force of the centrifuge outer wall compels
the material to deviate from that straight line and move in a circle.
The centripetal force ("center seeking") is real, and is what causes the
material to move in a circle.


Just because something is coordinate dependent it
does not mean it is not "real".

Sure it does! Arbitrary human choices of how to describe a real
phenomenon cannot possibly affect the phenomenon itself.


Calling the last two terms in my equation above "forces" does not make
them so. <shrug>

It seems that in order for you to support you false argument you will
go out of your way calling forces that everyone feels every day in a
car, in an amusement park, riding a bicycle, unreal.

You have _NEVER_ felt "centrifugal force". What you have felt is the
door of a car pushing sideways on you as the car turns a corner. Etc.
All of these "fictitious forces" have that character -- nobody _ever_
feels them (because your nerves sense differences, and these "forces"
are all proportional to mass and thus there is no difference for your
nerves to feel; what you feel is other forces which are _always_ in the
opposite direction: your chair pushes up, the car door pushes toward the
_inside_ of the curve, etc.).


Besides containing several innacuracies and basic physics errors, your
neurophysiologicallly based assertions to defend an absurd postion show
desperation.

I suggest to you getting a ride in one of those holocoasters. Sure, you
will feel getting pushed against the side of your cart. But when you
feel your lips and cheeks getting tweested you will understand the
power of the centrifugal force.

When you accelerate forward in your car, the little voodoo head hanging
from your rear-view mirror by a string swings backwards. Why does it do
that?

I'm glad you've notices that.




One person might say there is a force backwards on the voodoo head. Of
course, one is hard pressed to find the agent of such a backwards
force. What would be pushing backwards?

Agent 007


Another person might say that in order for the voodoo head to keep up
with the car, a force has to be applied to it to make it accelerate
forward. The only agent available for such a force is the string.
Unfortunately, a string can only pull along its length and so a
vertical string cannot possibly apply a horizontal force required for
horizontal acceleration. Now, if the string were to be inclined, so
that its length were partially vertical and partially horizontal...

Someone is "pulling the strings then". Some "agent"...

Which explanation makes more sense?

The explanation I gave before in the case of the marry-go-around
experiment which I suggest you read it and understand it.

If you and Roberts have any doubts theat a coriolis force for example
is a real force all you have to do is watch the water go down the sink
drain. Actually its rotation direction is different in the north and
south hemisphere, this shows that water molecules are clearly affected
by this real force which Einstein misunderstood and ended up
transforming away.

Actually, Einstein did no such thing. He didn't have a lot of comment
about the Coriolis force.

As for whether the force is real or not, I suggest you take a friend to
the playground for an experiment. Sit on a merry-go-round and toss a
playground ball across the rotating platform while you stand on it.
You'll need a third person standing on the ground to observe the motion
of the ball through the air and ask whether this person sees any force
acting on the ball.

http://archive.ncsa.uiuc.edu/Cyberia/DVE/FusionDVE/html/coriolis_force_lesson_plan.html

PD

.

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