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  1. Sep 29, 2016 #1
    Ok, im sure similar questions have been asked but here it goes.

    You start digging a hole with the intention of digging straight through the planet. Your hole will be straight but will only go through the mantle, missing the core and outer core, so you have avoided the weightlessness of the earth's core. So what happens? you keep digging down and you get closer the surface on the other side of the world. Do you at some point fall back? when do you become upside down?
     
  2. jcsd
  3. Sep 29, 2016 #2

    davenn

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    depending on where you dig from and to, you may be digging sideways

    consider this ....

    upload_2016-9-30_9-11-51.png


    you cannot drill at 90 deg to the surface and miss the inner or outer core
     
  4. Sep 29, 2016 #3

    phinds

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    What do you think and why?
     
  5. Sep 29, 2016 #4
    So lets say you start about 2 thirds to the left or right of the YOUR DRILL HOLE point. That would mean your hole is vertical and misses the core.
     
  6. Sep 29, 2016 #5

    phinds

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    I'm not getting any sense out of that. Draw it.
     
  7. Sep 29, 2016 #6

    davenn

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    not sure what you mean
    take my drawing and alter it to show me
     
  8. Sep 29, 2016 #7
    I have no idea. Can't get my head around it.

    The philae lander was held to a small comet by a small amount of gravity. Probably enough to hold a person. So if 2 people at each end of the comet started digging through it then eventually their feet would be touching. Like one is on the second floor and the other person on the ground is standing on the ceiling.

    Weird
     
  9. Sep 29, 2016 #8
    I saved your earth image and altered it on paint. How do I upload it on here?
     
  10. Sep 29, 2016 #9

    DrGreg

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    Do you mean like this?

    upload_2016-9-30_9-11-51.png
    You do realise that "vertical" means towards the centre of the Earth, not towards the bottom of the piece of paper you draw the diagram on?
     
  11. Sep 29, 2016 #10
    Yes, that's what i meant.
     
  12. Sep 29, 2016 #11

    jbriggs444

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    So what about @DrGreg's question -- do you realize that drill hole is not vertical?
     
  13. Sep 29, 2016 #12
    The point is to dig a hole that you could fall through without touching the sides, that is not at an angle and misses the core.

    I could ask what would happened if you could dig a hole straight through the earth's core but I think that question has been answered.
     
  14. Sep 29, 2016 #13

    davenn

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    but it is and has to be at an angle to the Earth's surface ( as I said earlier)
    you cannot dig/drill a hole that is vertical (perpendicular) to the surface and not miss the core

    look again at my drawings my original and the one Dr Greg rotated ... BOTH ends of the hole are at an angle to the surface

    we just need you to get that sorted and understood, before tacking the gravity issue


    Dave
     
  15. Sep 29, 2016 #14

    phinds

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    Glad to see I'm not the only one who manages to say the opposite of what he means. :smile:
     
  16. Sep 29, 2016 #15

    Dale

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    There is no such hole. If you can fall through it without touching the sides then the hole is vertical. If it is vertical then it points towards the core.
     
  17. Sep 29, 2016 #16

    davenn

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    ?? .... did I err ?
     
  18. Sep 29, 2016 #17
    I think this is all going off topic a bit and too much is being discussed about my "vertical" hole, what im interested in is what would happen to the person digging, he can be digging on any body that has enough gravity to keep him grounded. So for example, he could be digging through the Rosetta comet, ad on the other side a person is also digging a hole. Eventually there holes will meet. From person A's POV person B is digging up and he is digging down. If they both jumped into the hole they'd land on each other's feet. Now if they are both lowered into the hole using a lift/elevator there feet will be on the floor of it, but as they get closer eventually they become upside down, so do they fall toe the ceilings of their lifts?
     
  19. Sep 29, 2016 #18

    Dale

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    The person digging the hole shown in post 9 is not digging a hole per se, but rather they are digging a tunnel. That tunnel slopes downward at one end, is level in the middle, and slopes upwards at the other end. The digger could stand on one side the whole way, assuming they had enough traction at the ends.
     
  20. Sep 29, 2016 #19

    phinds

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    Well, maybe it's just that we interpret differently the use of too many negatives in the sentence. What I heard after removing the negatives was "if you dig a hole vertically, it will miss the core"

    Convoluted language is MY job. Please be more straightforward in the future :smile:
     
  21. Sep 29, 2016 #20

    davenn

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    you may be right :oops:

    I will do better sir phinds :-p:-p
     
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