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Does Falling Speed Differ from speed?

  1. Jul 28, 2014 #1

    This is a quick question that I want to know,
    When an object falls, does the vertical falling speed stay the same with any horizontal speed?

    To be more clear about this question, this is an example:
    There is a bullet.
    1. The bullet falls from 10 meters above the ground without any change in rotation.
    2. The bullet is fired from 10 meters above the ground, again without any change in rotation.

    I know that it will hit the ground at the same time if there is no air resistance but I don't know which one will hit the ground earlier where there is air resistance? Will the speed of the bullet matter? Does air actually make it fall slower?

    Thank you.
    Last edited: Jul 28, 2014
  2. jcsd
  3. Jul 28, 2014 #2
    Yes air will make it fall slower, but in the case of a bullet, very little. Friction always acts directly opposite to the direction of motion.

    For your question, you can break the forces up into their components. There is an initial force horizontally when the bullet is shot, so friction will oppose in the horizontal direction. There is also a gravitational force pointed downwards, where the friction is opposing upwards. When the bullet isn't shot, there will be no horizontal force, but that will not effect the vertical force.
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