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Beyond the norm Dynamics question

  1. Sep 24, 2012 #1
    Hey Guys,
    I have tough dynamics question. I wasn't sure if this is the best place to post it, so if it isn't please let me know. I thought it might be because I couldn't find anything about it anywhere. So here goes. If one had 10 inch long hose, 1" in diameter, filled with some incompressible fluid, like hydraulic oil, and capped both ends when the pressure was at 100 psi, how much weight could the hose support with a weight suspended from one end and the opposite end anchored into the wall, before it started to bend? Assume that the caps and the hose will be able to withstand all the pressures equally without bursting. From what I understand it could support a weight equal to the pressure in the hose, but I am not certain how to work it out mathematically. Any help would be great. Thanks in advance!
  2. jcsd
  3. Sep 24, 2012 #2


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    Staff: Mentor

    Based on a dimensional analysis: ##F = c p \frac{d^3}{l}## where c is some numerical constant (I would expect that it is between 1/5 and 5), p is the pressure, d is the diameter of the hose and l is its length. With SI units, it is easier to calculate.
    ##m=\frac{F}{g}## with ##g=9.81\frac{m}{s^2}##.
  4. Sep 24, 2012 #3
    Hi, thanks for the reply. It all makes sense, except c, the numerical constant, how do I determine that? by experimentation or a material constant?
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