Does the Earth's speed of rotation alter the effects of gravitational forces?

Question

In other words, if the Earth's speed of rotation were to slow, would the effects of gravity increase, or does the centrifugal (or centripetal) force caused by the Earth's rotation have no effect on gravity?

Answer 1

It depends on where you are. If you are at the North or South poles then your axis of rotation is along the line of gravitational force so rotational forces, being perpendicular to the axis of rotation, do not affect your apparent mass (the force you exert on the ground divided by g) - its equal to your actual inertial mass.

If you are standing on the equator, then your axis of rotation is perpendicular to the line of gravitational force and rotational forces have their maximum effect. About 1 thousandth of the gravitational force is needed as centripetal force to produce the rotation (keep your feet on the ground) so you will see a tiny difference in your apparent mass - the remaining 999/1000 of your inertial mass.

In order for you to fly off, the earth's rotation would have to speed up 30 fold at which point the centripetal force exerted by gravity would be insufficient to compensate for your linear momentum. Wheeeee!!

Answer 2

Just as an illustration, here is the formula for centripetal acceleration:
a=v^2/r

a=(463.9)^2/6378750m
a=0.0337m/s^2
g=9.8m/s^2
a is 0.34% of g.

This is at sea level at the equator. This value will quickly get smaller as your latitude increases, because both the radius of rotation AND the linear velocity decrease. (No matter where you are, it takes 24hrs to make 1 complete trip).

Not only that, but as your latitude increases, the direction of "centrifugal force" is less and less in line with the direction of gravity, so this rapidly decreasing force will have a rapidly decreasing percentage of its effect on your weight. In other words, it becomes negligible very quickly.

For Chicago, (assuming a spherical Earth) the reduction in acceleration due to Earth's rotation is .025m/s * cos(latitude) = 0.019 m/s^2, or 0.19%

Earth would have to rotate once every 84.48 minutes in order to make you weightless at the equator.

Answer 3

The strength of gravity is just that and it is doubtful u would be able to measure what effect the earth speed makes.

Answer 4

It has no effect on Earth's gravity.

Answer 5

There is *some* effect at the equator that's measureable, but you probably wouldn't feel it much.

Gravity itself isn't affected, but your weight is.

Answer 6

well, why not look at it this way.
if it stoped spinning what then.