Locomotion: Dealing with friction

Abstract

To move on land, in water, or in the air, even at constant speed and at the same level, always re- quires an expenditure of energy. The resistance to motion that has to be overcome is of many different kinds depending on size, speed, and the characteristics of the medium, and is a fascinating subject in itself. Even more interesting are nature's stratagems and solutions towards minimizing the effort involved in the locomotion of different types of living crearures, and man's imitations and inventions in an attempt to do at least as well.