The investigation is experimentally verifying Poiseuille's equation. The independent variable is the changing pressure and the dependent variable is flow rate.
My experiment plan is having a simple buchner flask (cylindrical flask labelled measurement with a pipe at bottom). I will fill the flask with a fluid whilst the nozzle on the pipe is closed. I will also have a motion sensor attached to the top of the flask to see the change in height. As pressure is related to height; Pressure = (density* height* gravitational acceleration). This will tell me the changing pressure.
To find the flow rate at each point in time, I will beforehand see how much volume is reduced per millimeter of height change using a ruler. Knowing this I will be able to use the height to calculate the flow rate, which would be my dependent variable.
Is this a valid experiment? My concern is that since both my variables are coming from the change in height, I might just be fooling myself instead of seeing how the pressure changes flow rate.