27 February 2006

Questions you didn’t even realise you needed answering

No. 42 What would happen if I drilled a tunnel through the center of the earth and jumped into it?

1 Comments:

Blogger guurgle said...

Although it would be impossible to do this on earth, you actually could do this on the moon. The moon has a cold core and it also doesn't have any oceans or groundwater to complicate things. In addition, the moon has no atmosphere, so the tunnel would have a nice vacuum in it that eliminates aerodynamic drag.
So, imagine that you drilled a tunnel through the moon. Imagine that, down one side, is a ladder. If you were to climb down the ladder, you would find that your weight decreases. Because gravi¬ty is caused by objects attracting one another with their mass, as you descend into the tunnel, more and more of the moon's mass is above you, so it attracts you upward. Once you climb down to the center of the moon, you would be weightless. The mass of the moon is all around you and attracting you equally, so it all cancels out and you would be weightless.
If you were to actually leap into the tunnel on one side of the moon and allow yourself to fall, you would accelerate toward the center at a very high speed. Then you would zoom through the center and start decelerating. You would eventually stop when you reached the tunnel's lip on the other side of the moon, and then you would start falling back down the tunnel in the other direction. You could oscillate back and forth like this forever, or you could grab the lip on the other side.
If you could do this on earth, one amazing effect would be the ease of travel. The diameter of the earth is about 7,800 miles (12,700 kilometers). If you drilled the tunnel straight through the center and could create a vacuum inside, anything you dropped into the tunnel would reach the other side of the planet in just 42 minutes! People could travel from the U.S. to China or India in less than an hour, for free!

19:09  

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