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Question:
The gravitational acceleration at earth's surface is 9.8 m/s/s. The centripetal acceleration on earth's surface at the equator is 0.006 m/s/s. At earth's equator the gravitational force and the centripetal force are both in the same vertical direction. However, at other places on earth's surface the centripetal force is at an angle equal to a place's latitude, and the centripetal force is reduced due to reduced distance to the axis of earth's rotation. One would deduce that at these places there's a horizontal component of centripetal force, that would cause a person to lean slightly toward earth's pole to maintain his or her balance. Has this phenomenon been confirmed by experiment? At what latitude is this phenomenon the greatest?



Replies:
This probably goes under the name of Coriolis force. You are pushed to the right in the northern hemisphere. So if air is moving in towards a low pressure, it is pushed to the right, so it begins to swirl counter clock wise (like a hurricane). Its a pretty weak effect, you don't notice it, but a lot of air the size of a state does.

Steve Ross


It certainly is true, and it is evidenced by the Earth's oblateness - its slight flattening at the poles. In other words, the Earth is not a perfect sphere: its shape is basically spherical, but with a little bit of a pancake shape mixed in. So "up" on Earth is just a tiny bit toward the axis away from the direct line from where you are to the Earth's center. Exactly at what latitude this phenomenon is greatest is a terrific question - and I do not know the answer.

Richard Barrans



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