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  • Challenger Deep reached again

    http://wonderwall.msn.com/movies/james- ... 3267.story

    A T&F connection (well, kind of a stretch.) I read somewhere long ago that a 16 lb shot, dropped in the Pacific over the Deep, would take 60 minutes to reach the bottom.

  • #2
    Re: Challenger Deep reached again

    I dropped out of HS physics (made my head ache, didn't' need the credits), but.... would it take longer or shorter for a 12-pound shot to drop?

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    • #3
      Re: Challenger Deep reached again

      Making various simplifying assumptions, I get something like 30 min. to reach bottom for the 16 lb shot. If made of the same material, the 12 lb shot should reach a slightly lower terminal velocity, take ~5% longer to make the same journey.

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      • #4
        Re: Challenger Deep reached again

        Originally posted by catson52
        Making various simplifying assumptions, I get something like 30 min. to reach bottom for the 16 lb shot. If made of the same material, the 12 lb shot should reach a slightly lower terminal velocity, take ~5% longer to make the same journey.
        Does its smaller size (less surface friction) help it?

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        • #5
          Re: Challenger Deep reached again

          Originally posted by Marlow
          Originally posted by catson52
          Making various simplifying assumptions, I get something like 30 min. to reach bottom for the 16 lb shot. If made of the same material, the 12 lb shot should reach a slightly lower terminal velocity, take ~5% longer to make the same journey.
          Does its smaller size (less surface friction) help it?

          Terminal velocity appears to depend on both the mass and the "surface area" of the object. In the given case, the mass difference (in the numerator), seemed to more than offset the "surface area" difference (in the denominator).

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          • #6
            Re: Challenger Deep reached again

            And, by the time it got to the bottom, how much would the pressure reduce the ball's diameter?

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            • #7
              Re: Challenger Deep reached again

              Originally posted by kuha
              And, by the time it got to the bottom, how much would the pressure reduce the ball's diameter?
              Probably the most obscene thing I have ever read!
              phsstt!

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              • #8
                Re: Challenger Deep reached again

                Originally posted by kuha
                And, by the time it got to the bottom, how much would the pressure reduce the ball's diameter?
                It would probably shrink to the size of a black hole and swallow the entire earth, which means you wouldn't have to make coffee tomorrow.

                But seriously, it is about 15 lbs per square inch at sea level and 35,000 ft. deep is about 1200 atmospheres. So about 9 tons per square inch. So a little smaller assuming it is solid steel, or better even iron. As for one of those indoor shots? Forget it. I think it would like a vitamin pill by the time it hit bottom.

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                • #9
                  Re: Challenger Deep reached again

                  The key thing for shrinking under pressure is the density of the shot, which is about the same for all of them, and the ability of the material to resist compaction (the surface material on the indoor shot would become thinner, however). I would guess that most of the materials will not shrink much because they have a lot of internal support. [note how little water compacts]

                  As for the surface area/volume, since the mass factors as the cube and the cross-section as the square of the linear dimension, it should have increased force per unit of area offering resistance.

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                  • #10
                    Re: Challenger Deep reached again

                    60 minutes seemed a bit long to me. I can picture a shot descending a lot more rapidly than 7 mph.

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                    • #11
                      Re: Challenger Deep reached again

                      Originally posted by DrJay
                      60 minutes seemed a bit long to me. I can picture a shot descending a lot more rapidly than 7 mph.
                      I was thinking that myself. I would bet it is closer to half an hour or less.

                      Anyone want to experiment in their bathtub? :lol:

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                      • #12
                        Re: Challenger Deep reached again

                        does it make a difference if you drop it with the spin style as opposed to the glide?

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                        • #13
                          Re: Challenger Deep reached again

                          If it hit you after dropping 35,000 + feet would it hurt more than from, say, 35 feet?

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