A crane can move a crate with a mass of 2200 kg with a force of 500 N. The second crate has a mass that is 4 times larger. What would the second crates acceleration be?

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.