A 1:16 model of a bus is tested in a wind tunnel in standard air. The model is \(152 \mathrm{~mm}\) wide, \(200 \mathrm{~mm}\) high, and \(762 \mathrm{~mm}\) long. The measured drag force at \(26.5 \mathrm{~m} / \mathrm{s}\) wind speed is \(6.09 \mathrm{~N}\). The longitudinal pressure gradient in the wind tunnel test section is \(-11.8 \mathrm{~N} / \mathrm{m}^{2} / \mathrm{m}\). Estimate the correction that should be made to the measured drag force to correct for horizontal buoyancy caused by the pressure gradient in the test section. Calculate the drag coefficient for the model. Evaluate the aerodynamic drag force on the prototype at \(100 \mathrm{~km} / \mathrm{hr}\) on a calm day.