New personal record today.

[AKIron]

Ok, how about for rotational inertia of a spinning earth? Did we assume no friction in this tube?



That was a little vague, I'll clarify. Because on the surface of the earth you are moving faster than a point say halfway to middle of the earth you will exert force on the side of the tube as you fall. If we create a maglev tube perhaps this force becomes negligible.

[Jebus]

What the hell did you two just say?

English Boy

[AKIron]

Originally posted by Jebus
What the hell did you two just say?

English Boy

The ride to the middle of the earth will be like a water slide, only scarier.  

[rogwar]

The temp was around 75 to 80 degrees. Zero at the top. They pump huge amounts of air down into the mine.

It will eventually bottom out around 10K feet underground.

The wild thing is there are like miles of tunnels at the 7,000 foot range.

Had to go down there to recommend some equipment. I work with the mining and cement industries in the area of instrumentation and process control.

[B@tfinkV]

Originally posted by Chairboy
Yep.



The gravity at any radius r less than Rearth  will be linearly proportional to the distance from the center.

(per http://hyperphysics.phy-astr.gsu.edu/hbase/mechanics/earthole.html)

ok ok uncle! uncle!  you win

Originally posted by Chairboy


 

although....


this diagram shows the center object being pushed equaly in all directions.

your arrows should be reversed? or is the 'pull' of gravity expected to be coming fom the surface of the earth and not the center?

confusing eh?

think of an object in orbit, the arrows would need to be pointing inward toward the CoG to make sense. the object in orbit is being pulled by gravity the same as us falling out of a tree.

but not by the earth's surface, the earths surface acts as a barrier to stop us being pulled to the center, hence we can walk on it.

so really are your arrows not showing a push from the center in all directions, and not a pull from the surface of the sphere?