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Q & A: gravity and the spinning earth

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Most recent answer: 10/22/2007
Q:
If the earth is rotating counter clockwise, and we are on the crust or outside of the earth, why doesn’t everything on the crust of the earth fly of into space?
- Kena (age 12)
Raleigh, N.C.
A:
Actually, whether you say the earth rotates clockwise or counterclockwise depends on whether you view it from the North or South directions.

Anyway, stuff (like us) on the earth doesn't fly off because the force of gravity holds us down. If the Earth were spinning much faster, gravity wouldn't be strong enough and we would fly off.

The earth does bulge a bit at the equator for exactly this reason, and the effective gravitational field strength is a bit less at the equator (you'd weigh a tiny bit less at the equator than you do in North Carolina for two reasons -- one is that you're speed of going around in circles is faster, and the other is that you are farther away from the center of the earth).

Mike W. and Tom

(published on 10/22/2007)

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