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After reaching the local terminal velocity, while continuing the fall, speed decreases to change with the local terminal speed. Using mathematical terms, defining down to be positive, the net force acting on an object falling near the surface of Earth is (according to the drag equation ):
At any given density of air, the terminal velocity of a person is much lower than that of a heavy spacecraft. This is because starting from a stationary platform means that fall speed never exceeds the local terminal velocity (though this is quite high in thin atmosphere) and a small light body slows down relatively quickly as the atmosphere ...
The boost phase is the portion of the flight of a ballistic missile or space vehicle during which the booster and sustainer engines operate until it reaches peak velocity. . This phase can take 3 to 4 minutes for a solid rocket (shorter for a liquid-propellant rocket), the altitude at the end of this phase is 150–200 km, and the typical burn-out speed is 7 k
For a potato-shaped object of average diameter d and of density ρ obj, terminal velocity is about =. For objects of water-like density (raindrops, hail, live objects—mammals, birds, insects, etc.) falling in air near Earth's surface at sea level, the terminal velocity is roughly equal to with d in metre and v t in m/s.
So, for a human in belly-to-earth position (A = 0.7 m 2, m = 90 kg, C d = 1) this gives 50.6 m/s, about the terminal velocity of the typical skydiver of 55 m/s. The skydiver cannot increase their mass easily enough to significantly increase terminal velocity, and the skydiver's area cross-section is limited by their helmet and shoulders in a ...
The terminal velocity depends on many factors including mass, drag coefficient, and relative surface area and will only be achieved if the fall is from sufficient altitude. A typical skydiver in a spread-eagle position will reach terminal velocity after about 12 seconds, during which time they will have fallen around 450 m (1,500 ft). [4]
Maximum bluntness (minimum ballistic coefficient) also yields a minimal terminal velocity at maximum altitude (very important for Mars EDL, but detrimental for military RVs). However, there is an upper limit to bluntness imposed by aerodynamic stability considerations based upon shock wave detachment .
English: Graph of the velocity versus time of a skydiver reaching terminal velocity. The time evolution is given by = ...