Straight through the middle of earth??

[barrsp]

I have wondered this for a long time.

If I dug a large round hole all the way through the middle of the earth and out the other side, with my very tough heat proof suit and spade,  What would happen if I dropped a large cannon ball down it.  Would it stop in the middle where the centre of gravity is or would it fall upwards and out through the other side.

Thanks

[boobesque]

it will bounce back and forth for a while as if on elastic, then eventually it will stop in the middle due to the gravitational pull.

[MargeB]

Pretty original question...good one!

[bernardo]

It would accelerate until it got to the centre of the Earth, continue out towards the other side, and gradually decelerate until it reaches the other side.  It wouldn't quite get far enough to "pop out" the other side.  The resistance from the air inside the tunnel would cause it to slow down gradually.  It would be a bit like letting go of a pendulum and letting it swing-swang backwards and forwards until it gradually rests in the middle.

[stevie21]

Why is this question being asked once a week? Is it in a quiz or something or are people all having the same odd puzzle to themselves independently?

[jenstar]

Never mind air resistance - I'd be more worried about the moving liquid metal of the Earth's outer core. If you can force a cannonball through that then you're doing very well indeed.

[jake-the-peg]

Ah but would it be spinning?

[Sion]

Try it and see

[boobesque]

if this was on the moon however or another body with no atmosphere, the cannonball would indeed pop out the other side to the exact height from the ground as the height that you dropped it at. The gravity would once again pull it back into the centre and back out to the side which you initially dropped the ball from, once again at exactly the same height. This would go on indefinitly as long as the gravity that pulls the ball towards the centre is equal to the gravity which stops the ball at the other end.

T