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Feather Vs. Anchor

  1. Dec 27, 2004 #1
    hey guys, if i drop 2 objects at the same height, regardless of mass they will drop at the same time. but if i drop a anchor and a feather, isn't there anything holding up the feather to make it drop later than the anchor?
  2. jcsd
  3. Dec 27, 2004 #2


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    Yes. Air slows the feather. But drop them both in a vacuum and they will fall at the same speed.
  4. Dec 27, 2004 #3
    Both will hit the ground at the same time if they are dropped from the same height in a vacuum. In daily life, an anchor hits before the feather because the feather is slowed down by air resistance more than the anchor is.

    Edit: Krab posted at the same time as I did.
  5. Dec 27, 2004 #4


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    Technically even in a vacuum the achor hits just a tiny bit before the feather, since it pulls the earth toward its more than the feather does. For objects this small, and realtive small distances, you probably can't measure the difference. but take a feather and something the size of the moon, from about 200,000 miles away from the earth, and the moon and the earth will collide first.
  6. Dec 27, 2004 #5
    But I thought there was no gravity/air in space.
  7. Dec 27, 2004 #6


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    There is gravity everywhere but air is not.From what i know,interstelar/intergalactic space is the best possible example of thermodynamic "vacuum".There's about one particle (never mind what kind) every cubic kilometer of space... :wink: He wanted to say that,for comparable masses of the 2 objects,the CM of the system would not coincide with the heavier one's and so,the time untill impact would be smaller for the body with heavier mass.However,for planetary systems,the celestial bodies do not come crashing into each other according to Newton's attraction law,as the the gravity force is balanced by the centrifugue inertial force,the two forces balancing each other in an noninertial reference frame.

    Last edited: Dec 27, 2004
  8. Dec 27, 2004 #7


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    It is the earths gravitation which keeps the moon in orbit, the suns which keeps the earth and all the planets in orbit. Beyond that the sun is orbiting the center of the galaxy. Gravity is a weak force but very long ranged.

    You cannot speak of air and gravity as if they are related. Space is a vacume, this means that there are very few molecules or atoms per cubic meter. The particles which are there are effected by gravity.
  9. Dec 27, 2004 #8


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    There is, of course, gravity in space - its what keeps the earth orbiting the sun and moon orbiting the earth. What you're probably thinking of is the weightlessness of astronauts - that's due to gravity as well! If you're in space, the earth's gravity is keeping you in constant freefall and thus you feel weightless.
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