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Author Topic: increasing the range of the water leaving your hosepipe.  (Read 3036 times)

paul.fr

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Out watering my sisters jungle, oops garden. I know that by putting my finger over the end of the hosepipe, the jet of water will go further. But why does it?


 

Offline JP

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increasing the range of the water leaving your hosepipe.
« Reply #1 on: 07/08/2007 23:27:23 »
It's because water is a pretty incompressible liquid.  Let's say that every second your hose is turned on, a gallon of water flows into it.  Since water doesn't compress much when you put your finger over it (and assuming there's no leaks) a gallon has to come out of the open end of the hose every second as well.  Now, if you put your finger over the end, you restrict the amount of water that can flow out the end, so it has to flow out faster to get that gallon out per second.  Since it's moving faster, it goes further.

 

Offline Atomic-S

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increasing the range of the water leaving your hosepipe.
« Reply #2 on: 10/08/2007 07:35:22 »
But this process has some kind of a limit, because one cannot increase the velocity of the jet without limit by making the size of the hole approach zero. I suspect that the limit is the velocity such that when the hose is pointed directly up, the jetting water will reach a maximum  altitude equal to the height that the water would rise in if fed into a tall vertical pipe.  That is because of conservation of energy: neglecting frictional losses, the energy of the water leaving the restricted hose is equal to what it had before leaving, so that if jetted vertically, when it finally comes to rest it must have the same energy that it would have had in the enclosed hydrostatic situation.
 

Offline syhprum

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increasing the range of the water leaving your hosepipe.
« Reply #3 on: 10/08/2007 21:12:11 »
I think we can take an electrical analogy by viewing the hosepipe as a resistor fed from a constant voltage source.
When the nozzle is open it is equivalent to a low value terminating resistor and the majority of the (voltage) pressure is lost along the hose.
When the nozzle is reduced (equivalent to a high value termination) there is much reduced flow and consequently much reduced loss of pressure along the hose.
 
 

The Naked Scientists Forum

increasing the range of the water leaving your hosepipe.
« Reply #3 on: 10/08/2007 21:12:11 »

 

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