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Re: Ballistic Theory and the Sagnac Experiment

Subject: Re: Ballistic Theory and the Sagnac Experiment
From: Henri Wilson
Date: Thu, 30 Mar 2006 08:27:29 GMT
Newsgroups: sci.astro, sci.physics.relativity, sci.physics
On Wed, 29 Mar 2006 22:38:45 +0200, "Paul B. Andersen"
<paul.b.andersen@xxxxxxxxxxxxxxxx> wrote:

>Henri Wilson wrote:
>> On Mon, 27 Mar 2006 23:28:08 +0200, "Paul B. Andersen"
>> <paul.b.andersen@xxxxxxxxxxxxxxxx> wrote:
>> 
>> 
>>>Henri Wilson wrote:
>>>
>>>>On Wed, 22 Mar 2006 16:42:29 +0100, "Paul B. Andersen"
>>>><paul.b.andersen@xxxxxxxxxxxxxxxx> wrote:
>>>>>
>>>>>In a frame rotating with the angular velocity w (a vector)
>>>>>we have the following pseudo forces acting on a body with mass m
>>>>>which is moving with the velocity u (a vector) in the rotating frame:
>>>>>
>>>>>The centrifugal force:
>>>>> F = m* (w X (w X r))  where r is the radius vector.
>>>>> The magnitude of this force will be m*w^2*|r|, and
>>>>> its direction will always be radially outwards.
>>>>> Expressed with the speed v = |w|*|r| : F = m*v^2/|r|
>>>>
>>>>
>>>>Paul, that is centripetal force. (you omitted the minus sign somewhere)
>>>>
>>>>In the rotating frame, w = 0.
>>>
>>>I am obviously talking to an idiot.
>> 
>> 
>> w is the rotation of the R frame in the nonR frame as measured in the NonR
>> frame.
>> 
>> The R frame has no rotation in itself.
>
>>>>
>>>>>The Coriolis force:
>>>>> F = 2*m*(w X u)
>>>>>
>>>>> Note that the direction of this force always is
>>>>> in the plane of rotation, and is perpendicular to
>>>>> the velocity u. When u is tangential as in our case,
>>>>> the direction will be radial.
>>>>
>>>>
>>>>But in the case of a rotating sphere, such as Earth, it is NOT always in 
>>>>that
>>>>plane.
>>>>You calculation applies to the force due to change in angular momentum in 
>>>>the
>>>>NonR frame. 
>>>>Coriolis is the imaginary equivalent in the R frame (where w is again zero).
>>>>
>>>>
>>>>
>>>>>This NG is a sci group.
>>>>>When you discuss in this group, you better use the normal
>>>>>accepted definitions of centrifugal and Coriolis,
>>>>>don't invent your own.
>>>>
>>>>
>>>>Paul, in the R frame, w = 0. Do you disagree with that.
>>>
>>>You are an idiot!
>>>"In a frame rotating with the angular velocity w (a vector).."
>> 
>> 
>> ....w as measured in the NonR frame, the angular velocity is zero (in ITSELF,
>> the R frame).
>
>OK, Henri.
>Please explain what wisdom you tried to convey with
>your very intelligent remarks above.
>
>Please state which pseudo forces are acting on a body
>with mass m moving with the velocity u in a frame rotating
>with the angular velocity w (a vector).
>
>My answers, which you claim to be wrong, are:
>The centrifugal force:
>  F = m* (w X (w X r))  where r is the radius vector.
>  The magnitude of this force will be m*w^2*|r|, and
>  its direction will always be radially outwards.
>The Coriolis force:
>  F = 2*m*(w X u)
>  The direction of this force is always in the plane
>  of rotation, and is perpendicular to the velocity u.

No, you are now not wrong. I never said your figures were wrong, just your lack
of understanding.

You have accepted they are 'pseudo forces'.
You obviously use 'psuedo' so that you wont have to admit that I was right by
telling you they were 'imaginary'...same thing really.

>
>Please state the correct answers.
>
>Centrifugal force = ? (magnitude and direction)

that is equal and opposite to centripetal force in the non-rotating frame.

>Coriolis force = ?    (magnitude and direction)

I will not dispute your equations.

>
>Paul


HW.
www.users.bigpond.com/hewn/index.htm



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