Pookie was reading this thread over my shoulder and she thinks she has the 
answer.  When we play the game of throwing the ball on the house and she 
catches it,  she seems to know just how far from the house the ball is going 
to land..  And now she tells her secret.

She learned that the higher on the roof the ball lands and starts it roll, 
the faster it is going when it hits the gutter cover and comes straight off 
the roof.  So she thinks you could simulate the water falling a distance 
than converting that down speed to a across speed by rolling a marble down a 
ramp from the height of the water column, rolling across a small part of the 
table to get it to go horizontal, and look at it's path.

But then, Pookie is just a dog.

Bill
with Pookie's insight

----- Original Message ----- 
From: "Spehro Pefhany" <speff@interlog.com>
To: "Microcontroller discussion list - Public." <piclist@mit.edu>
Sent: Wednesday, March 01, 2006 7:26 AM
Subject: Re: [OT] Homebrew fountain help


> At 07:46 AM 3/1/2006 -0500, you wrote:
>>Mike Hord wrote:
>> > In particular, I'm wondering about an equation describing the
>> > behavior of a stream of water emerging from a hole in a
>> > reservoir.  Google search terms are proving elusive.  It seems to
>> > me that the equation should be pretty simple, based on depth
>> > of water and size of hole.  The result should be a half-parabola.
>>
>>Once you have the velocity of the water as it leaves the hole, plain old
>>highschool physics will give you the parabola.  The speed of the water 
>>would
>>be a function of the pressure and probably the diameter at small 
>>diameters.
>>I don't know how to compute that, but a few simple experiments should be
>>able to provide the answer relatively quickly.
>
> There's a square-root law between the pressure across an orifice and
> the flow rate. Since it's subsonic, Bernoulli's equation for 
> incompressible
> flow will probably be close enough (in reality the flow will be a somewhat 
> less
> for real fluids such as water by 10-40%, and there are tables published
> for correction).
>
> The maximum height an ideal fluid jet goes to is calculated here from
> Bernoulli's equation:
> http://highered.mcgraw-hill.com/sites/dl/free/0072454261/132215/cen54261_ch12_web.pdf
> In particular, see page 17.
>
>>Best regards,
>
> Spehro Pefhany --"it's the network..."            "The Journey is the 
> reward"
> speff@interlog.com             Info for manufacturers: 
> http://www.trexon.com
> Embedded software/hardware/analog  Info for designers: 
> http://www.speff.com
>
>
>
>
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