A researcher is interested in fish propulsion mechanics. To determine the thrust produced by a given fish, based on fish size ( L= fish length) and tail swing frequency ( f, in rev/s), constructs a mechanical model by taking the length of the geometry L=1m. It then fixes this model in a specific position in a large tank of still water at room temperature, measuring the thrust F over a wide range of tail swing frequencies. Find a dimensionless relationship between these quantities using pi theory (density and viscosity are also variables)