Hi, This is not homework, it's for myself. I'm trying to understand it for me only. I have a piston that is translating in a cylinder and pushing/sucking air through a nozzle. It's much comparable to a bicycle pump. The piston is moving with non-linear (exponential) velocity until it slams against the cylinder wall. I need a formula to find the air velocity at the end of the nozzle in function of time. I have tried using Bernoulli's principle, but it does not apply because we are dealing with a compressible flow. And I'm not sure how pressure builds up, as the airflow through the nozzle 'negates' the pressure buildup Also the volume and position (even velocity?) of the air particles in the cylinder change in time, so that means it's an unsteady flow? I have looked at the unsteady flow equation but I can't seem to understand it either. Help is appreciated.