A 20-cm-diameter smooth sphere is rigged with a strain gauge calibrated to measure the force on the sphere. Estimate the wind speed in 20-C air if the gauge measures (a) 4 N and (b) 0.5 N.
An automobile travels on a horizontal section of highway at sea level where the temperature is 20-C. Estimate the horsepower needed for a speed of 100 km/h. Make any needed assumptions.