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Hp of hose

  1. Nov 1, 2008 #1
    if i have a hose that is 1" in diameter, and 7 ft long before coming to a U section 4 inches high, and I have this hose full of water standing vertically, how much horse power does this hose of water contain?
     
  2. jcsd
  3. Nov 1, 2008 #2

    russ_watters

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    Staff: Mentor

    Power is a rate of energy expenditure. A static vertical tube is not expending any energy, but it does have a potential energy due to the height of the water column. Potential energy is just mgh.

    I don't understand what you are saying about the geometry of the hose, so I can't help you calculate the energy in it. However, if the hose were completely vertical, the average height would be 3.5 ft and the potential energy 8ft-lb.

    [edit] Since 1 horsepower is 550 ft-lb/sec, if the hose emptied in one second, it would generate an average of .016 horsepower for that second.
     
  4. Nov 1, 2008 #3
    I dont know how you get 8 ft lbs. can you explain? and what is mgh and why is it only in that unit?
     
  5. Nov 1, 2008 #4

    russ_watters

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    Staff: Mentor

    Multiply the area of the hose by the length to get volume (be sure to convert to cu ft). The weight density of water (already has "mg" in it) is 62.4 lb/cu ft. Average height 3.5. Multiply that all out...

    m=mass
    g=gravitational acceleration
    (put them together and you get weight)
    h=height

    Units are whaver you want (I used what you used), just keep them consistent.

    [edit] Oops, wait - this isn't homework, is it?
     
  6. Nov 1, 2008 #5
    no its not homework. I just need to know how much hp is potential energy in this hose.
     
  7. Nov 1, 2008 #6

    Dale

    Staff: Mentor

    Horsepower is a unit of power, not a unit of energy.
     
  8. Nov 1, 2008 #7
    well then how much energy is it?
     
  9. Nov 1, 2008 #8

    Dale

    Staff: Mentor

    8 ft-lb. As russ watters calculated above.
     
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