Aug 25, 2017

Wordology, Terminal Velocity

You close your eyes and jump. You feel yourself in free fall, hurtling toward Earth, open your eyes and see the ground slowly getting closer. You seem to be picking up speed as you fall and soon you hit terminal velocity. It is the velocity at which you stop accelerating. It describes a physical reality based upon Newton's First Law of Motion.

When an object falls freely through a medium, such as water or air, the force of gravity pulls it toward Earth. As the object falls, its velocity increases as it accelerates toward Earth.

Gravity is not the only force working on the object. Air molecules collide with the falling object, pushing it upward against gravity. Scientists call this force air resistance. As the velocity of the falling object increases, so does air resistance.

Eventually, air resistance will equal the weight of the object in free fall. When this occurs, the object reaches terminal velocity. This means the falling object has reached its maximum velocity. The object will continue to fall at the same speed (terminal velocity) for the remainder of its free fall, until it hits Earth or a parachute opens.

Terminal velocity can be affected by a few different factors. For example, a heavier object will generally have a higher terminal velocity and a smaller surface area will have a higher terminal velocity than a larger surface area.

Most skydivers reach a terminal velocity of about 125 miles per hour. Experienced skydivers who streamline their bodies during free fall have reached speeds of over 200 miles per hour.

During October, 2012, Austrian skydiver Felix Baumgartner jumped from a helium balloon in the stratosphere, twenty four miles above Earth. Because the atmosphere at that height is so thin, there is next to no air resistance at the beginning of the free fall. This allows the skydiver to reach a much higher terminal velocity before encountering Earth's normal atmosphere far below.

On Baumgartner's skydive, he reached an estimated top speed of approximately 843.6 miles per hour.

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