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    Re: Coriolis and gyros (second attempt)(typos corrected)
    From: Gary LaPook
    Date: 2009 Aug 24, 19:29 +0200

    There is a problem with your analysis.
    Since the period of the pendulum is fixed by its length then it is 
    necessarily true that as the amplitude of the swing diminishes during 
    the day, due to air resistance, that its maximum velocity and its 
    average velocity also slows down. Try this yourself with any pendulum 
    and observe how slowly it moves near the end as it slows to a stop. The 
    formula for coriolis force includes a term for velocity across the 
    turning reference frame so that coriolis force and coriolis acceleration 
    is proportional to this velocity over the ground. So if your analysis is 
    correct then the rate of change of the azimuth of the pendulum's swing 
    should vary throughout the day, changing at a more rapid rate in the 
    morning and more slowly later in the day as the pendulum slows down. But 
    the rate of change of azimuth is constant, 11.32 degrees per hour which 
    disproves your analysis.
    Now looking at the case of the gyroscope's undergoing earth rate 
    apparent precession. If this apparent precession  is caused by coriolis 
    due to the speed of the rotating flywheel moving in one direction at the 
    point at the bottom and in the opposite direction at the top, (as you 
    claim) then, without doing the diagram of the precessional forces (I 
    leave that to you), it must also be true that gyroscopes spinning in 
    opposite directions would also precess in opposite directions. One 
    rotating clockwise would precess toward the east and one turning 
    counterclockwise would precess toward the west yet all gyroscopes, no 
    matter which way they are spinning, precess toward the east, again 
    disproving your analysis.
    A further disproof of your analysis of earth rate precession of a 
    gyroscope is due to that pesky term in the coriolis formula that makes 
    the coriolis force proportional to velocity over the ground. If your 
    analysis were correct then slowly turning gyroscopes would precess more 
    slowly than rapidly spinning gyros yet they all show the same apparent 
    precession due to the earth rate of 15.04 degrees per hour times the 
    sine of the latitude.
    You have not addressed the movement of a gyrocompass at the equator 
    where coriolis is zero since the sine of zero degrees of latitude is 
    also zero, there's that pesky coriolis formula again.
    Also consider the earth rate apparent precession of a gyroscope at the 
    north pole which changes at a rate of 15.04 degrees per hour since the 
    sine of 90 degrees of latitude is 1. Yet a gyroscope located exactly at 
    the pole is not moving at all (ignoring the earth's movement around its 
    orbit) but is remaining at one fixed spot on the earth so it has no 
    velocity across the ground so, again by the formula, there should be no 
    coriolis available to cause the apparent precession.
    frankreed@HistoricalAtlas.com wrote:
    > "Coriolis is not involved since the Pantheon has not moved across the 
    surface of the earth since its foundations were laid in 1758 so its ground 
    speed is zero."
    > LOL. Gary the pendulum bob is itself in motion, right? Its ground speed is 
    most certainly NOT zero. Likewise in a gyro-compass, its individuaL mass 
    elements are moving at very high speed. If they weren't moving, it wouldn't 
    work. The Coriolis acceleration causes the precession in both cases --in the 
    rotating frame of reference in which the Earth is fixed.
    > -FER
    > >
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