Atmosphere of EarthThe atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth creates pressure, absorbs most meteoroids and ultraviolet solar radiation, warms the surface through heat retention (greenhouse effect), allowing life and liquid water to exist on the Earth's surface, and reduces temperature extremes between day and night (the diurnal temperature variation). As of 2023, by mole fraction (i.
Froude numberIn continuum mechanics, the Froude number (Fr, after William Froude, ˈfruːd) is a dimensionless number defined as the ratio of the flow inertia to the external field (the latter in many applications simply due to gravity). The Froude number is based on the speed–length ratio which he defined as: where u is the local flow velocity, g is the local external field, and L is a characteristic length. The Froude number has some analogy with the Mach number.
Neil ArmstrongNeil Alden Armstrong (August 5, 1930 – August 25, 2012) was an American astronaut and aeronautical engineer who in 1969 became the first person to walk on the Moon. He was also a naval aviator, test pilot, and university professor. Armstrong was born and raised in Wapakoneta, Ohio. He entered Purdue University, studying aeronautical engineering, with the U.S. Navy paying his tuition under the Holloway Plan. He became a midshipman in 1949 and a naval aviator the following year.
Ejection seatIn aircraft, an ejection seat or ejector seat is a system designed to rescue the pilot or other crew of an aircraft (usually military) in an emergency. In most designs, the seat is propelled out of the aircraft by an explosive charge or rocket motor, carrying the pilot with it. The concept of an ejectable escape crew capsule has also been tried. Once clear of the aircraft, the ejection seat deploys a parachute. Ejection seats are common on certain types of military aircraft. A bungee-assisted escape from an aircraft took place in 1910.
