Eddy viscosity is proportional to the square of one value of this quantity in a model named for it developed by Prandtl. The square root of little g times one value of this quantity appears in the denominator of the Froude number that models ship behavior. Ballistic electrons have a large value of one form of this quantity relative to the surrounding material. The ratio between two characteristic values of this quantity defines the (*) Knudsen (-5[1])number and determines if continuum mechanics apply. This quantity times dynamic viscosity over kinematic viscosity defines the Reynolds (-5[1])number. The average value of this quantity between collisions in a gas (10[1])is the mean free (-5[2])path. For 10 points, the volume of fluid inside a pipe equals cross-sectional area times what quantity with units of meters? (10[4]0[1])■END■