Determine the specific gravity of spherical particles, D=(1/200 in), which drop through air at 33degrees F at a speed U of 0.3 ft/s. The drag force on a small sphere in laminar motion is given by 3(pi)(mu)DU.
This problem is in Fluid Mechanics by Victor Streeter.
This boils down to our most favorite of Newton's Laws. Force equals mass times acceleration (F=ma). The force is given by 3(pi)(mu)DU. Where mu is the dynamic viscosity of air at ...
This solution discusses in 129 words how Newton's law can be applied to this question in finding mass, volume, and density to find specific gravity.