Could Rapid Spinning Affect Gravity on the Moon?

[nution]

Of, so the Earth has gravity because of its mass, but what does the effect of the spinning of the Earth cause on gravity. Wouldn't thinking about centrifugal force make you think that the extreme speed we are spinning mixed with how far we are from center have some effect on us out on the edge?

Like for the sake of argument, what if we could somehow force the moon to start spinning rapidly on an axis. What effect if any would that have on the gravitational forces on and around the moon? Would it weaken or strengthen or have no effect at all? It seems to me that rapid spinning would have some effect?

 

[JaredJames]

Gravity is weaker at the equator than at the poles due to the rotation of the planet. But the Earth doesn't spin fast enough to have a pronounced effect.

If the Earth spun faster the effect would certainly become more exagerated and the effective gravity would certainly reduce further at the equator.

I suggest you have a read through this first:
http://en.wikipedia.org/wiki/Gravity_of_Earth

At latitudes nearer the equator, the outward centrifugal force produced by Earth's rotation is stronger than at polar latitudes. This counteracts the Earth's gravity to a small degree, reducing downward acceleration of falling objects. At the equator, this apparent gravity is 0.3% less than actual gravity.

It covers everything you are asking here.

 

[Sakriya]

The apparent acceleration due to gravity due to rotation of the Earth is given by:
g(apparent)= g(standard) - R*ω^2*(cosA)^2
where R is radius of Earth at the point. A is angle made by the latitude with the equator and ω is orbital velocity. So, g is least at equator and max at poles because A=0 at equator and A=90 at poles.

 

[Nabeshin]

Also, in case you are interested, there is an actual (above posts discuss apparent gravity) gravitational increase due to an object's angular motion. The effect is general relativistic, and can be loosely described by saying that to spin an object you have to put energy into it, and energy corresponds to mass, so the object should have more gravity (don't take this simple explanation too far, but hopefully it's enough for you to get a grasp on it). As with most relativistic effects, the impact on our every day life is absolutely negligible, as you would have to be spinning the Earth at speeds comparable to that of light to get noticeable effects.

Of course, there's also the much more complicated phenomenon of frame dragging, which we've been trying to measure for quite some time now. You can read more about it here: http://en.wikipedia.org/wiki/Frame-dragging

 

[robdean]

To try and make it more intuitive one can reflect that despite one's 'speed' at the equator, one only completes a single rotation in 24 hours.

Picture driving a car at 100mph around a circular circuit with a circumference of 2400 miles - you're moving fast but you won't experience much 'centrifugal force'...

 

[JDługosz]

Read "Mission of Gravity", a classic by Hal Clement.