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Physics of Free Fall

Physics of Free Fall

Credit: US Navy
Source: http://commons.wikimedia.org/wiki/File:US_Navy_110625-N-DB458-127_Marines_jump_from_an_H-53_Sea_Stallion_helicopter_during_a_routine_sky_diving_evolution.jpg
License: CC BY-NC 3.0

These marines are in free fall until they open their parachutes. They are speeding toward Earth because of gravity.

The Back Story

  • Being in free fall makes you feel weightless. But why would you feel weightless when you’re being pulled by Earth’s gravity? After all, weight is defined as the force of gravity pulling you toward Earth.
  • True weightlessness occurs only in the absence of gravity. However, feeling weightless is something else. In free fall, you only feel weightless.
  • Credit: Rod Herrea
    Source: http://www.flickr.com/photos/herrea/4554946026/
    License: CC BY-NC 3.0

    You can experience freefall and weightlessness in a plane that is descending very quickly [Figure2]


  • What is it like to feel weightless? This video clip from a free-fall wedding shows what it’s like:


Can You Apply It?

At the link below, learn more about the physics of free fall. Then answer the questions that follow.

  1. What is free fall? Give an example.
  2. What gives you your sense of weight?
  3. Why do you feel weightless during free fall?
  4. Are astronauts in the International Space Station weightless or do they just feel that way? Explain.
  5. What could you do in free fall that you couldn’t do otherwise?

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