Gravity inside the Earth?

Question

If someone could dig a hole through the earth and dropped something in how would gravity affect it.

Answer 1

I read a book that dealt with this question. If you could dig a hole right through the center of the earth, if you jumped in you would fall faster and faster until you got to the center. Then you would begin to slow down, you'd fall slower and slower and you'd stop just as you got to the surface on the other side. If you didn't grab on, you'd then fall in the other direction.

But if the hole was filled with air there would be a certain amount of energy lost to wind resistance, so you would get -almost- to the other surface on the first fall, and a little lower on the next, and you'd oscillate back and forth, a little less each time, until you came to rest in the center of the earth. At that point you'd have a lot of climbing to do. 8^)

If the hole didn't go through the center of the earth, but just -through- the earth, you would still fall through. The path would be shorter, but the effect of gravity pulling on you would be less, so it would take the same amount of time for each trip!

Answer 2

Apart from the fact that the liquid core would keep filling it up, or that in the center of the liquid core a high density iron core recides?

An object thrown in a perfectly centered tunnel would accelerate until it reached terminal velocity.
With this speed it would pass the center and b able to fly away from the center but not nearly far enough to reach the other side. It would then fall back and very soon it would end up in the center where it would float weightlessly since in the center of the perfect tunnel, the earth' mass would pull on the object from all sides evenly.

The tunnel would need to be from pole to pole. And the earth would be perfectly smooth... and the moon would have to be gone.... all the planet and nearby stars as well.

Without those arrangements, the object would slowly bend off from it's path and hit the side of the tunnel.

Answer 3

The force of gravity would decrease gradually until it reached zero at the center. If the earth's density were uniform, the force would be directly proportional to radius.