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Help needed! (Motion of a marble underwater)

  1. Oct 1, 2005 #1
    Can anyone give me an explanation of why a marble dropped into a swimming pool will fall faster than if you drop a marble into a water filled tube with a diameter only slightly larger than the marble itself (presume it doesn't touch the walls of the tube). It's something to do with how quickly water can be displaced, but I can't come up with a good explanation.

  2. jcsd
  3. Oct 1, 2005 #2


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    Gold Member

    You're pretty much there. Try thinking of a similar but different scenario. What would be the effect of setting off a firecracker beside a ping-pong ball as opposed to putting them both into a narrow tube and lighting it? Why?
  4. Oct 2, 2005 #3
    Thanks, I understand now :)
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