Terminal Velocity

When something falls through the air toward the ground, the force of gravity makes it accelerate. As it accelerates, the drag (air resistance) it experiences increases. If it falls for long enough, its weight is exactly balanced by drag, and it stops accelerating. This velocity is called its terminal velocity.

A large but very light object, such as a feather, reaches its terminal velocity very quickly. A heavier object of the same size has a higher terminal velocity, because a higher speed is needed to cre­ate enough drag to balance its weight.

In the usual skydiving position­falling with arms and legs held out-a skydiver’s terminal velocity is about 120 miles per hour (195 kilometers per hour). With arms and legs pulled in, however, there is less drag, and the skydiver accelerates. Terminal velocity increases to about 200 miles per hour (320 kilo­meters per hour) before weight and drag are once again balanced.

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SEE ALSO:

• Gravity • Laws of Motion

• Relativity, Theory of • Skydiving

• Speed

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