# Hoping to verify valve specs

1. Apr 20, 2010

### axemaster

Ok, so I'm building a pneumatic gun with a barrel 0.3m long, operated using air pressure. The barrel is square, 1cm on each side, and the projectile is a 5g elongated cube. I wrote some code in mathematica to plot the speed in m/s versus the air pressure in psi.

I was wondering if anyone could verify that my calculations are accurate, and if not, where I may have gone wrong. I'm pretty confident, but as I'm spending money on this I want to be sure.

The mathematica code is below:

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(*Variables;
x is the distance over which it accelerates;
m is projectile mass in kg;
area is area that the force acts on in cm (square barrel 1cm on each \
side);
*)

x = .3;
m = .005;
area = 1;

(* Constants and conversions *)
psiToPascalsConstant = 6894.7573;

pressforce[pressure_] := (pressure*psiToPascalsConstant)*
area; (* gives N *)

velocity[force_] := ((force/m)*Sqrt[(2 x)/(force/m)])/100;

Plot[velocity[pressforce[psi]], {psi, 0, 150},
AxesLabel -> {Psi, Velocity}]

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Thanks for your help!

-Axemaster