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Phy hw help

  1. Sep 6, 2005 #1
    K. I was given the problem:

    An egg is thrown nearly vertically upward from a point near the cornice of a tall building. It just misses the cornice on the way down and passes a point a distance 50.0 m below its starting point at a time 5.00 s after it leaves the thrower's hand. Air resistance may be ignored.

    And i'm trying to find: What is the initial speed of the egg?

    so i used the equation Xf=Vo*t+Xo ie: 50+Vo*5+0 getting 10 m/s, but that answer is wrong.

    so then i tried Xf= Xo+Vo*t+(1/2)a*t^2 ie 50=0+Vo*5+.5*9.8*5 assuming a=9.8 but that wasn't given. i got 34.5 and that was wrong too. So if anyone has any idea as to what i'm doing wrong or how to get the correct answer let me know.

    thanks
    clair_a_net
    ps if its after 12pm tonight then the hw was already due so thanks for trying anyways. but i would still like to know what im doing wrong.
     
  2. jcsd
  3. Sep 6, 2005 #2

    Fermat

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    Homework Helper

    You have,

    50=0+Vo*5+.5*9.8*5

    which I assume is just a typo (for the power of t = time) and that you actually used

    50=0+Vo*5+.5*9.8*5²

    this gives

    50 = 5Vo + 122.5
    5Vo = -72.5
    Vo = -14.5 m/s
    ===========
     
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