how fast must the earth spin to neutralize gravity?

Increasing the rotational speed of the earth will not neutralize gravity. You are assuming that gravity is created by the rotation of the earth. This is incorrect. Gravity on earth is caused by the earth warping space and time. Please be advised that the person who stated that gravity is electromagnetic is wrong; gravity is one of the four forces of Nature.

It doesn't work like that. The forces that cause gravity are electromagnetic. What we feel is ourselves being pulled down to the core of Earth, and pulled up towards our ionosphere. When the Earth first started out way back in the day the core was relatively devoid of electrons (as much as it could be) and the layer of oil in our planet acted as an insulator between the core and the surface. On the surface, a large amount of electrons and "ether" or dark energy came flowing in.

The layer of electrons and ether were attracted to the core, and wanted to reach it but could not because of the oil layer. They stuck to the surface like the water pressure pushing in on a submarine. This is where fluid dynamics comes in, and we were able to bounce around in this relatively dense layer of electrons. Gravity felt much lighter, and as a result our planet was able to support such massive beast as the Ultrasaur and Teratorn, which would crush themselves under their own weight in our present gravity.

Also, the other planets like Mars and "Krypton" (the asteroid belt now) were able to be seen from the ground. After their electric destruction they appeared to be banished from the Heavens, but before then we could see them in the sky. They interacted with our planet and affected our gravity by pulling us up into the sky a little bit. Since gravity is really an electromagnetic force, the upward pull felt by us here on the Earth was evenly distributed throughout the entire ionosphere. We felt ourselves being pulled up a little less than we were being pulled down to the core.

Hope this helped you understand what gravity really is, and hopefully you can research this new idea a little more thoroughly on your own. Gravity IS IS IS electromagnetic, all forces must be unified somehow. The mainstream science these days sucks, read up on the "Electric Universe" theory. Don't stop reading up on it right away though, the more you read the more sense it makes.

***Please be advised the guys below me are wrong. There HAS to be a relationship between all the forces we know of: strong force, weak force, electromagnetism and gravity. This is what scientists have been looking for for the longest time, and have yet to find. When I say electromagnetism I'm speaking generally, because it's easiest to see what causes the other 3 forces by investigating electromagnetism more thoroughly. Our planet has a large *** magnetic field, and I'm supposed to believe it has nothing to do with gravity?***

The faster it spins, the more likely it would be that we would overcome gravity and fly off into space.

And, gravity isn't electromagnetic. It's one of the four fundamental forces - which include electromagnetism. Gravity pulls you towards a center (of gravity), spinning pushes you away from the center (of rotation)

[edit]

well, if the asker is asking at what point the centrifugal force would overcome gravity I'd have to run some numbers...

Gravity is NOT electromagnetic.

If I did my calculations right, you need to travel 7901 m/s relative to the ground to orbit "on the ground"

[Scientists have been looking for a connection between gravity and electromagnetic forces because the equation for the law of gravitation is almost identical to the equation for electromagnetic force/fields and only varies by a constant and the characteristics of the object involved. That doesn't mean gravity is electromagnetic though. If that were the case then neutron stars would not be massive]

I believe what lax4life0022

is asking is what speed the earth would have to spin so that the centripetal acceleration is equal to the acceleration due to gravity. The answer to this depends on where on Earth you are. The centripetal force near the equator will be the highest.

I going to average this out for the readers - how about extremely fast!

1000 miles an hour to be exact

speed in day. 1day per day