You now immerse the interferometer in a tank filled with some unknown liquid and carefully align the laser into the interferometer. you move the mirror until you count 100.0 fringes passing the crosshairs of the telescope. the micrometer indicates that the mirror has moved 0.02381 millimeters. what is the index of refraction for this mystery fluid

Engines for propeller-driven aircraft are limited in their maximum rotational speed by the fact that the tip speed of the propeller must not approach the speed of sound in air (mach i). taking 6 ft as a typical diameter for a propeller of a light airplane and 1100 fils as the speed of sound, find the upper limit on the rpm (revolutions per minute) of the propeller shaft.