If a basketball player has a vertical leap of 1.56 meters, then what is the total amount of time he spends in the air? (Note: the acceleration due to gravity on Earth is -9.81 m/s/s)

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.