Convert from dekameter/day to mach

Unit Definition (dekameter/day)

Unit Definition (mach)
The Mach is a measure of velocity relative to the speed of sound. The precise speed of sound varies with the density and temperature of the atmosphere, although at 0 °C (at 1atm.) the speed of sound is 331.6 m/s. The mach speed is important to the control of an aircraft, especially at speeds close to or exceeding Mach 1.0. The unit is named after the Austrian physicist Ernst Mach.