Phys101
Since: Apr, 2010
Jun 23rd 2012 at 6:35:46 AM
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The title (at least) is bad. Whenever there exists a "terminal velocity," that terminal velocity is always variable, because there's always air resistance. The force of air resistance depends on numerous properties (shape and size of the falling object, density and viscosity of the fluid, etc.) What's invariant is the gravitational acceleration in vacuum.
On skydiving: when I did my AFF jumps, I was notified to be "extremely fast descender" and the instructors were suggested to wear extra weights. I was advised to wear as coarse jumpsuit as possible to create as much drag as possible, and not to bend the torso too much. The terminal velocity is dependent of the air resistance and drag coefficient, and the larger the drag coefficient, the slower the terminal velocity. (Needless to say, parachutes have very large drag coefficients. Otherwise every jump would end up in bounce.)
Edited by morane