Aisha is sailing with her motorboat at a speed of 14 m/s when she suddenly sees a swimmer appearing 24 meters away. It reacts after
0.9 seconds and then puts the engine into reverse at full throttle. The
braking distance is then 12 m.
Explain whether Aisha stops on time and explain your answer with a
calculation.

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.