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Q: Height required to achieve terminal velocity ( Answered,   4 Comments )
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 Subject: Height required to achieve terminal velocity Category: Science > Physics Asked by: pomakis-ga List Price: \$10.00 Posted: 13 Dec 2002 10:35 PST Expires: 12 Jan 2003 10:35 PST Question ID: 124248
 How high does an average limp person have to fall from to hit the ground at terminal velocity? Honestly, I'm only asking this question out of pure curiosity, and so I can point out to acrophobic friends that being on a balcony on floor x is no more life-threatening than being on a balcony at floor y. I'd like to know what the minimum value of y is for this statement to be true.
 Subject: Re: Height required to achieve terminal velocity Answered By: tar_heel_v-ga on 13 Dec 2002 11:24 PST
 Pomakis.. The terminal velocity of a falling body occurs during free fall when a falling body experiences zero acceleration. The magnitude of terminal velocity depends on the weight of the falling body. For a heavy object, the terminal velocity is generally greater than a light object. This is because air resistance is proportional to the falling body's velocity squared. There is much more to determining terminal velocity than simply body posture and height. There are, however, some rough estimates that you can use in order to prove your point to your friends. It is estimated that the human body will reach 99% of terminal velocity after falling 1,880 feet (573 meters) which takes anywhere from 10-14 seconds. With normal posture and normal atmospheric pressure, this is a speed between 117 and 125 miles per hour, or approximately 54 meters per second. Another source I found stated that a human would have to fall over 400 yards (1,200 feet) prior to achieving terminal velocity. Now, a building story is approximately 12.5 feet. Using the lower number of 1,200 feet and the very basic information above, you would have to fall from approximately the 96th floor balcony to achieve terminal velocity. Now, I am sure there will be a physics genius or two that will calculate the exact distance and speed required using in depth formulas, however, I feel that the above information (and the references below) should suffice for your friends. :) Thanks for you very interesting question and I hope the above information is helpful. If you need any additional clarification, please let me know. Regards, -THV Search Strategy: terminal velocity human References: The AFU and Urban Legend Archive Death - Falling Terminal Velocity http://www.urbanlegends.com/death/falling_terminal_velocity.html Speed of a Skydiver (Terminal Velocity) http://hypertextbook.com/facts/JianHuang.shtml Ask a Scientest - Falling Bodies http://newton.dep.anl.gov/askasci/phy00/phy00012.htm Physics Forum http://www.physicsforums.com/topic.asp?TOPIC_ID=7318