The drag force (Fd) acting on a spherical particle that falls very slowly though a viscous fluid is a function of a particle diameter, d, the particle velocity, V, and the fluid viscosity, u. Using dimensional analysis determine the Pi term(s) suitable to describe this problem.
Fd=f(d,V,u)
If an experiment shows that a drag force (Fd=3lbs) acts on a spherical particle (diameter=3 in.) falling through the water (V=2ft/s) at 70 degrees F (u=2.04x10^-5 lbs*s/ft^2) Using the non-dimensional correlation what would the drag force be on the sperical particle (diameter=0.25 in) falling through oil (V=.1ft/s) at 50 degree F (u=3.10X10^-3 lbs*s/ft^2)