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Homework Help: Independence of Motion

  1. Mar 16, 2008 #1
    [SOLVED] Independence of Motion

    I have a problem with a diagram that goes along with independence of motion. When air resistance is negligible, objects are supposed to fall at the same rate. In the diagram (a flash photograph), it shows 2 balls falling, one straight down, and the other horizontally. So, in my interpretation, they should fall at the same time still. But in the diagram, the horizontal one has 2 more flash's of itself, indicating it took longer to fall. I was able to find another diagram in the textbook with the same problem. So I was just wondering why it shows that.
  2. jcsd
  3. Mar 16, 2008 #2


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    they will take the same time to fall down at the condition that they have the same initial velocity along y!! If an object is dropped from rest and another object is thrown horizontally, they will take the same time to reach the ground (neglecting air friction).
    But if one object has some initial velocity along y (for example of the one moving straight down was actually thrown downward) then the times will be different
  4. Mar 16, 2008 #3
    Ok. They were released simultaneously, so now I've got to figure out if it's an error in the diagram. Thanks.
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