Re: Does the earth slow down?

"Greg Neill" <gneillREM@xxxxxxxxxxxxxxxxxx> wrote in
news:y66Re.2988$884.480830@xxxxxxxxxxxxxxxxxxxxx:

> "Douglas Manning" <douglaslmanning@xxxxxxxxx> wrote in message
> news:4314da0f$1@xxxxxxxxxxxxxxxxxxxxxxxxx
>> I recently read that the Earth spins faster on it's axis during the
>> month of September than it does during March. Is this possible? I
>> would think that inertia alone would preclude any such speeding up and
>> slowing down. Any comments, clarifications, or explanations on this
>> subject would be very much appreciated. Thanks for your time.
>
> Conservation of angular momentum is the key. If you
> shift the mass around (for example, change the average
> distance of the mass from the axis of rotation), then
> to conserve angular momentum, the velocity of rotation
> will change.
>
> Can you think of anything whereby some amount of the
> Earth's mass might be shifted about due to seasonal
> changes?
>
>

A non seasonal example is the recent earthquake that caused the Indian
Ocean Tsunami. The movement of the Earth's crust caused a change in the
Earth's moment of inertia and a measurable change in the Earth's rotation
rate.

Klazmon.
.

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