depression definition. A period of drastic decline in the national economy, characterized by decreasing business activity, falling prices, and unemployment. The best known of such periods is the Great Depression, which occurred in the 1930s.
A variometer â also known as a rate of climb and descent indicator (RCDI), rate-of-climb indicator, vertical speed indicator (VSI), or vertical velocity indicator (VVI) â is one of the flight instruments in an aircraft used to inform the pilot of the rate of descent or climb.
Speed is an expression of how fast an object moves. An object's speed is how much distance it travels in a certain amount of time. Units of speed include miles per hour (mph), centimeters per second (cm/sec or cm/s), meters per second (m/sec or m/s), or kilometers per hour (kph or km/hr).peed is an expression of how fast an object moves. An object's speed is how much distance it travels in a certain amount of time. Units of speed include miles per hour (mph), centimeters per second (cm/sec or cm/s), meters per second (m/sec or m/s), or kilometers per hour (kph or km/hr).