Astudent team is to design a human-powered submarine for a design competition. the overall length of the prototype submarine is 4.85 m, and its student designers hope that it can travel fully submerged through water at 0.4 m/s. the water is freshwater (a lake) at t = 15 °c. the design team builds a onefifth scale model to test in their university’s wind tunnel. a shield surrounds the drag balance strut so that the aerodynamic drag of the strut itself does not influence the measured drag. the air in the wind tunnel is at 25°c and at one standard atmosphere pressure. at what air speed do they need to run the wind tunnel in order to achieve similarity? at this air temperature, the speed of sound is around 346 m/s. determine the mach number of the flow.