On Sat, 4 Mar 2006 10:12:07 -0800, "Glenn"
wrote:


"Don Foreman" wrote in message
.. .
On Fri, 3 Mar 2006 19:30:19 -0800, (daniel
peterman) wrote:

You guy are about a million times smarter than I, but I got a question
wrong on a test years ago and it nags at me.
What would seem to be the more destructive force.
High pressure water or:
Massive water flow. IE volume
I guessed volume but it was wrong but I think the test was wrong.
It wasa long time ago and before I croak I need somee finality on this.

Bad question. In order to have a clear answer it would have to
state destructive to what.

Tsunamis do enormous damage with volume flow. However, a water jet
cutter can cut materials that would be imervious to less pressure
regardless of volume.

If you direct a garden hose fed by 60 PSI water at your house, the
house will merely get wet. If a 30-foot high tidal wave ( 15 PSI at
the root) moving at 50 mph hits your house -- bye bye house!

But the tidal wave is exerting way more total pressure on the house.

Total force, sure, because there is more area. Not necessarily
more pressure.

If water moving at 50 mph (73 ft/sec) is redirected to move
vertically, it would rise to a height of about 85 feet. s =
v^2/(2g) from high school physics and conservation of momentum. The
obstacle causing this redirection of momentum must therefore exert
the pressure necessary to do that, which would only be about 42 PSI.
Lower pressure but considerably more destruction.

Still begs the question of "destructive to what?" A pinhole leak in
a 2000 PSI hydraulic system, while having very low volume flow, can
easily inject hydraulic fluid into your eye. If it's your eye, you
may well argue that this is more destructive than getting doused with
10 gallons of fluid thrown from a bucket -- particularly if the bucket
isn't thrown along with the liquid.