The maximum velocity an object can reach while falling through the air
is called the "terminal velocity". As something falls though air, there
is an upward force on it due to the air itself (called air resistance).
The size of this force gets larger as the speed of the falling object
increases. Eventually, when the speed of the falling object is big
enough, the upward force due to the air will equal the downward force
due to gravity. When this happens the object won't speed up any more,
and will just keep falling with the same speed (the terminal velocity).
The terminal velocity depends on the object. That is because the air will affect some things more than others.
The terminal velocity of a skydiver is about 150 miles per hour.
This only takes them about 14 seconds to reach, but once there, they
don't go any faster. However, if they change the way their body is
positioned so that less air hits them, they will go a little faster.
Once they open up their parachute, the terminal velocity is much
smaller; small enough that when you hit the ground you don’t get hurt.
Adam
(published on 10/22/2007)
