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Homework Help: 2D Motion Physics Problem

  1. Nov 17, 2008 #1
    1. The problem statement, all variables and given/known data
    An arrow is fired with a horizontal spped of 89 m/s directly at a target 60 m away. When it is fired, the arrow is 1 m above the ground. How far short of the target is it when it strikes the ground?

    2. Relevant equations
    D = vt
    D = Vit + (1/2)at2
    Vf = Vi + at
    Vf2 = Vi2 + 2ad

    3. The attempt at a solution
    Basically my teacher says to set up a table, one side horizontal values and the other vertical values.

    The values I know for:
    • Horizontal - velocity = 89, distance = 60
    • Vertical - acceleration = -9.8, distance = 1

    Then that is where I get stuck...help? BTw the anser is 20 m short, but my teacher wants me to show work.
    Last edited: Nov 17, 2008
  2. jcsd
  3. Nov 17, 2008 #2


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    Staff Emeritus
    Science Advisor
    Homework Helper

    There are some more items to fill out in your table.

    Horizontal: time?
    Vertical: time?

    Also, there are a couple of problems with the values you do have.

    1. If the arrow falls short of the target, it does not go the full 60m distance.

    2. Acceleration is -9.8 m/s^2, so you are using upward=positive, downward=negative. But then you say the vertical distance travelled is +1m upward. Gotta watch those +/- signs.
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