Quote:
If you keep making it longer, the wall friction will keep increasing, while the end cap force will decrease by the same amount. Eventually the wall friction will dominate.


I didnt make it longer its 500 ft , let me check , brb

---- time passes ----

yep it was 500 ft from the begining

post #34663

Originally Posted By: paul
I think thats a load !!!

if I have a nozzle at one end of a long pipe and the entire pipe
is at 14.7 psi.

lets say the pipe is 60 inch diameter and 500 ft long.


Quote:
Eventually the wall friction will dominate.


the wall friction might dominate between the wall friction and the force felt by the pipe end as a small force that would subtract from the larger force that is generated as the compressed air exits the air tank and passes through the nozzle.

but the resulting force is why the pipe keeps moving.

Quote:
However you do it, after the pipe has traveled its length, there's no possibility that any of the air could still be going in the same direction it was when it left the tank, without having turned around at some point. That's where the length-of-pipe limit comes from. Just try to draw a picture of that, it's geometrically impossible!


that really makes no sence at all.

if i allow a burst of air to excape the tank the pipe would begin to move.

and there is nothing to stop the pipe from moving.

if I wait until the pipe has traversed its lenght and again allow another burst the pipe will accelerate even faster
and I could repeat this until the air in the air tank equalized with the air in the pipe.


Quote:
it's geometrically impossible!


true , which causes the single directional force of the air leaving the nozzle to be the dominant force when determining which force is the greatest force that would give momentum to the pipe.







Edited by paul (03/09/11 07:44 PM)
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3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.