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Effect of reservoir location on water throw from hose

  1. May 17, 2012 #1
    If a reservoir was at the top of a cliff and a house was immediately below it with another house at the bottom of the cliff would the latter throw the water further from a hose due to the steep descent?
  2. jcsd
  3. May 17, 2012 #2


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    Apart from energy losses in the pipes, the situation should be the same in all cases. The kinetic energy of the water leaving the hose (hence, the speed) would be equal to the Gravitational Potential Energy at the surface of the reservoir.

    A simpler example would be a car rolling down a frictionless slope. Whatever the profile of the slope (long and gentle or short and steep) the final speed would be the same. On the
  4. May 22, 2012 #3
    Well if I describe the question do you have any idea what it could mean? Might it mean the hose is sprayed from the reservoir?

    'At which house will a hose throw water further'?

    A reservoir is shown at the top of a cliff slightly below which is house A.

    Immediately below A there is a sudden drop (a cliff) at the bottom of which is house B.

    You have to choose between A, B or C (both). The correct answer is given as B however sadly there id no explanation. If the question means the hose is placed at the reservoir then B would make sense because the water travels in a straight path over the top of A before descending down on B?

    I wouldn't have thought a hose would throw water that far though. Therefore I presumed the question meant turning on a hose at either house and the difference in the throw of water between the hoses.

    Any suggestions? I can't provide further details as that is the extent of the diagram
  5. May 22, 2012 #4


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    You sure? The relative height of a water tower and the faucet from which we draw water does make a difference in the speed with which the water flows. Higher pressure at the lower location means more force acting on a a unit volume of water at the nozzle, hence more acceleration, greater speed, more kinetic energy. The greater speed translates into greater flow so the water level in the reservoir drops more quickly, transferring more potential energy per unit time.

    I may be reading OP's (less than perfectly clear) question differently than you. If so... never mind.
  6. May 22, 2012 #5
    That is what I thought. Makes sense then why house B (at the bottom of the cliff) is the correct answer
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