<Tr> <Td> Instantaneous velocity v i (\ displaystyle \ v_ (i) \) of a falling object that has travelled distance d (\ displaystyle \ d \) on a planet with mass M (\ displaystyle \ M \) and radius r (\ displaystyle \ r \) (used for large fall distances where g (\ displaystyle \ g \) can change significantly): </Td> <Td> v i = 2 G M (1 r − 1 r + d) (\ displaystyle \ v_ (i) = (\ sqrt (2GM (\ Big () (\ frac (1) (r)) - (\ frac (1) (r + d)) (\ Big)))) \) </Td> </Tr> <P> The first equation shows that, after one second, an object will have fallen a distance of 1 / 2 × 9.8 × 1 = 4.9 meters . After two seconds it will have fallen 1 / 2 × 9.8 × 2 = 19.6 meters; and so on . The second to last equation becomes grossly inaccurate at great distances . If an object fell 10,000 meters to Earth, then the results of both equations differ by only 0.08%; however, if it fell from geosynchronous orbit, which is 42,164 km, then the difference changes to almost 64% . </P> <P> Based on wind resistance, for example, the terminal velocity of a skydiver in a belly - to - earth (i.e., face down) free - fall position is about 195 km / h (122 mph or 54 m / s). This velocity is the asymptotic limiting value of the acceleration process, because the effective forces on the body balance each other more and more closely as the terminal velocity is approached . In this example, a speed of 50% of terminal velocity is reached after only about 3 seconds, while it takes 8 seconds to reach 90%, 15 seconds to reach 99% and so on . </P> <P> Higher speeds can be attained if the skydiver pulls in his or her limbs (see also freeflying). In this case, the terminal velocity increases to about 320 km / h (200 mph or 90 m / s), which is almost the terminal velocity of the peregrine falcon diving down on its prey . The same terminal velocity is reached for a typical . 30 - 06 bullet dropping downwards--when it is returning to earth having been fired upwards, or dropped from a tower--according to a 1920 U.S. Army Ordnance study . </P>

How far does a human fall in 3 seconds