Consider a smooth sphere, of diameter d, immersed in a fluid moving with speed v. the drag force on a 16-ft diameter weather balloon in air moving at 5 ft/s is to be calculated from test data. the test is to be performed in water using a 4-in. diameter model. under dynamically similar conditions, the model drag force is measured as 0.86 lbf. evaluate the model test speed and the drag force expected on th full-scale ballon.