[ExI] underwater sprinkler, was: RE: Musical instruments in space

[John Clark]

On Fri, Mar 8, 2013 at 9:26 AM, spike <spike at rainier66.com> wrote:


>  > You have seen those S-shaped lawn sprinklers, turn on the water, they
> spin.  What would happen if you took one of those, submerged it in water,
> connected the hose to a pump and pulled water thru it backwards?  Would it
> turn the opposite direction, since the tips of the arms would act as
> nozzles in reverse?  Or would it turn the same direction as before, since
> the water is creating centrifugal force as it goes around the bend?  Or
> would the forces exactly cancel and not turn?  Or a fourth possibility that
> blows your mind?
> I know the answer from experiment.  Can you figure it out from math and
> thought experiment?
>

It won't turn at all. When water is going out it is jetting outward in one
specific direction and thus because of the conservation on momentum there
is a force in the opposite direction which makes the sprinkler spin;
however when there is a suction and water is going in and not out the water
can come from any direction and thus there is no net momentum in any
particular direction and so there is nothing to make the sprinkler spin.

  John K Clark




>
> spike
>
>
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