Which landform represents the boundary between the land and an ocean or a lake?

Why do different substances have diffrent properties

Achild has maximum walking speed of 1.6 m/s. what is the length of the child's legs? 0.26 m

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.