Imagine that there's a 10' diameter hole that goes through the Earth....?

Question

from one side to the other, exactly through the center. Now, If I dropped a bowling ball into said hole, would it come out the other side? If not, what would happen to it?

Answer 1

It depends on where you place the hole. If you drilled from the north pole to the south pole (and assuming that you can insulate the shaft from the heat of the earth's core) and dropped the ball into the hole, it would fall back and forth, slowed a little by air friction each time, until it settled into what would appear like suspension at the center of the earth. At that point the gravity of the earth pulls from all directions and the object would be weightless. (You can treat the earth as a point source of gravity only if you're outside its surface, but not if you're inside the surface.)

The result would be a lot different if you drilled the hole from (say) a point on the equator to its antipodal point on the equator. The reason is that at the equator, just before you drop it the ball is moving eastward, relative to the center of the earth, with the rotation of the earth at a speed of about 1000 miles/hour. That rotational speed doesn't go away when you drop it into the hole. But the deeper you go, the slower the shaft is rotating about the earth's axis. 2000 miles down (halfway to the center), the shaft is rotating about the axis at only 500 miles/hour. As the ball drops it would start to scrape against the forward part of the shaft, and would rapidly lose momentum from the friction of the shaft. To have it fall down the middle of the shaft, you would have to build a helical shaft that took account of the varying rotational speed

There's also an effect from the tidal attraction of the moon, but I don't know how to calculate it.

Answer 2

ignoring any kind of drag force, it would fall out on the other side of the earth at the same height you dropped it from, and it would continue to oscillate back and forth indefinately. in reality if this were somehow possible, air resistance among other things would cause the bowling ball to oscillate back and forth with a decreased amplitude each pass until the ball settled down at the center of the earth.

Answer 3

It'll fall ALMOST all the way through to the other side. Then it will fall back toward you, but again, get not quite as far as it did last time. This will continue for a LONG time, until it finally stabilizes in the center of the earth.

Answer 4

It will oscillate from one side of the earth to the other - like it is on a giant spring.