Earth Tunnels

[Leader Bee]

Everybody has asked the question of what would happen if you were to drill a hole directly through the centre of the Earth and I find the answers fascinating, if not plausible.

 

But this isn't about a hole directly through the centre of the Earth. I'm curious to know what the effects of a long tunnel from maybe one side of a contenent to another (lets say Russia as that covers a large portion of Earths landmass)

 

I know that an in antipodal tunnel it's likely that you'd experience weightlessness but how would one perceive a perfectly straigth tunnel that didn't intersect Earths core? I beleive that even though the tunnel would be straight one would experience it as a U shaped tunnel going downhil at first, until the centre of gravity is reached whereupon it would appear or feel to rise again into an uphill slope.

 

with it being a straight tunnel i'm curious of this U shaped phenomenon and wonder if anyone else has had any thoughts on the subject?

[Sisyphus]

Yeah, your description is accurate. At the ends it would be angled downwards, and in the middle it would be level, while being straight the whole time. (The tunnel straight through the center is just a special case of that where the initial angle is straight down.) If the tunnel were frictionless, you could slide down it, gathering speed, then slow down in the second half, and come to rest again exactly at the surface.