Problem

The drag on a sphere moving in a fluid is known to be a function of the sphere diameter,...

The drag on a sphere moving in a fluid is known to be a function of the sphere diameter, the velocity, and the fluid viscosity and density. Laboratory tests on a 4-in.-diameter sphere were performed in a water tunnel, and some model data are plotted in Fig. P7.40. For these tests the viscosity of the water was 2.3 x 10^-⁵ lb s/ft² and the water density was 1.94 slugs/ft³. Estimate the drag on an 8-ft-diameter balloon moving in air at a velocity of 3 ft/s. Assume the air to have a viscosity of 3.7 x 10^-⁷ lb.s/ft² and a density of 2.38 x 10^-³ slugs/ft³.