Calculating Reaction Force from Fluid: Nozzle Size, Density, and Pressure

[NZBen]

Does anyone know how to figure out the reaction force from a fluid if the known variables are nozzle size fluid density and pressure?
Say as an example we are ejecting water at 100Bar from a round hole 2mm diameter (3.1416x10e-6 m^2)
Thanks in advance for any formulas :)

 

[Astronuc]

The thrust (force) is simply comes from the momentum equation.

Here are some basics - http://www.grc.nasa.gov/WWW/K-12/airplane/rktthsum.html