What does it mean to be financially responsible? It's a complex question with a complex answer, but at its core is a simple truth: To be financially responsible, you need to live within your means. And to live within your means, you must spend less than you make.
longitudinal axis. A straight line running fore and aft through the center of gravity. It is horizontal when the airplane is in the rigging position. The aircraft rolls about this axis. See axes.
Longitudinal Waves. Longitudinal waves are wave in which the vibrations of the particles or medium in which the wave travels are in the same direction as to that in which the wave travels. Sound waves are an example of longitudinal waves. The animation above shows sound waves travelling through air.