Terminal Velocity

ndbilly

March 07, 2002 05:22

I grew up believing that an object reached a maximum or "terminal" velocity of 120 mph when dropped from a point high enough to allow it to achieve that velocity. In other words, that's all the faster anything could go in a free fall.There was a show on The History Channel recently that told of early upper atmosphere experiments that included a free fall from a balloon at a height of +102,000 feet. The fellow who jumped, Kerrington, I think, reached a velocity of over 700 mph and broke the sound barrier in a 4 1/2 minute drop. Since my knowledge of physics is roughly equal to my knowledge of 10th Century Mayan pottery patterns, I was hoping someone out there might be able to explain this idea of terminal velocity in words of one syllable. Thanks.

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  badboybob

  March 07, 2002 05:47

  Terminal velocity varies in inverse proportion to atmospheric pressure. At high altitudes (low pressure) terminal velocity is higher than at low altitudes (high pressure). An object dropped from an altitude of 100,000 feet can reach a velocity exceeding the speed of sound AT THAT ALTITUDE, (the higher you go, the lower the speed of sound in air), but its speed will decrease as it enters denser air due to atmospheric friction.The terminal velocity of a falling object in air also varies according to its mass and sectional area. A kleenex won't fall nearly as fast as a grand piano.

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  PC=BS[This message has been edited by badboybob (edited 03-07-2002).]

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  niklasal

  March 07, 2002 07:56

  badboybod got it right.In layman's terms, there are less air molecules floating around, so when the body falls, it hits less air, thus a higher speed is achieved. The closer you get to the earth, the higher the pressure means the MORE air molecules floating around for the body to hit, and it slows you down. That's the simplest basis of wind resistance.

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  NIKLASAL@hotmail.com

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  rsnyder55

  March 07, 2002 09:42

  I believe the 120 mph figure that gets passed around is the terminal velocity for recreational parachuters at normal altitudes

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  ndbilly

  March 07, 2002 12:35

  Thanks, boys.

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  Xracer

  March 08, 2002 05:25

  The terminal velocity for 10th Century Mayan Pottery (in a vacuum) is 32 feet per second, per second.

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  Blokey

  March 08, 2002 05:31

  Xracer,Actually, that's the acceleration due to gravity for 10th Century Mayan Pottery (in a vacuum)

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