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Homework Help: Concept question

  1. Dec 10, 2007 #1
    i have a concept question that i cant seem to get anybody?? Know??

    Lets say you and a friend are wacthing tv and see an astronaut on the space station let go of a pen while he turns to get some paper. What happens to the pen when the astronaugt lets go of it? Your friend says its because there is no gravity up there. Explain why your friend is wrong?
  2. jcsd
  3. Dec 10, 2007 #2
    It is because the space station is in orbit. It is still in the gravitational field, so it is in free-fall, not zero-gravity.
  4. Dec 10, 2007 #3
    There is gravity everywhere, the pen "floats" because it is in free-fall, similar to a skydiver as he/she plummets towards the ground. The pen is constantly falling towards earth however because the shuttle the pen is in is orbiting the earth it's moving fast enough to not crash into the earth. But yes there is gravity on the pen.
  5. Dec 10, 2007 #4
    thanxs guys

    thnak you so its like the shuttle cause a centrifugal force which keeps the pen up
  6. Dec 10, 2007 #5

    It's the same as if you were in a free falling elevator and dropped a pen. You and the elevator and the pen are falling toward the earth, but to you it seems as if the pen isn't falling becasue you are falling just as fast as it.

    The space station in orbit is constantly falling towards the earth, but its perpendicular velocity is such that its motion is an orbit instead of a line direct to earth.
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