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- Thread starter dmayers94
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- #2

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If gravity were the only force acting on an object at the earth's surface, it would be pulled down into a much tighter "orbit." One with a radius much smaller than earth's. But this is not possible since contact forces with the ground counteract gravity somewhat, and they balance so that we stay on the surface of the earth at all times.

- #3

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This formula is not supposed to give you g.

you get g at a distance R from the earths centre using g=GM/R^2

where M is mass of earth

G is the Universal Gravitation constant.

For g at surface we use R as radius of earth.

What you are calculating by a=w^2*R is something entirely else.

You have calculated the centripetal acceleration felt by a particle moving in a circle of radius R at the same angular frequency as that of earth.

That has no reason to be g.

Infact its the centripetal acceleration a person on equator will have wrt to the Centre of Mass of earth (but we don't feel as we are at rest relative to earth's surface and because its too small) cause we are rotating with earth.

you get g at a distance R from the earths centre using g=GM/R^2

where M is mass of earth

G is the Universal Gravitation constant.

For g at surface we use R as radius of earth.

What you are calculating by a=w^2*R is something entirely else.

You have calculated the centripetal acceleration felt by a particle moving in a circle of radius R at the same angular frequency as that of earth.

That has no reason to be g.

Infact its the centripetal acceleration a person on equator will have wrt to the Centre of Mass of earth (but we don't feel as we are at rest relative to earth's surface and because its too small) cause we are rotating with earth.

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http://en.wikipedia.org/wiki/Centrifugal_force

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