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Homework Help: Golf ball physics problem

  1. Sep 17, 2006 #1
    A golf ball is released from rest from teh top of a very tall building. Choose a coordinate system whose origin is at the starting point of the ball, and whose y axis points vertically upward. The acceleration of gravity is 9.8 m/s^2. Neglecting air resistance , calculate the velocity of the ball after 2.84s. ANswer in units of m/s.
    ---ok basically i have tried this question about 3 times and each time i have gotten it wrong. The first two answers made absolutely no sense and the third answer i got was 185.3543
    this is how i did it:
    Vf= 9.8m/s^2(2.84s)^s
    = 60.27392
    then i did
    60.27392^2= 2(9.8 m/s^2x)
    i got 185.3543
    ----
    please reply asap i have no clue how to solve this- i thought i was correct but apparently not. what formulas should i use? How would i go about to getting the answer? THANKS SO MUCH
     
  2. jcsd
  3. Sep 17, 2006 #2
    V = V_o + GT
    DeltaY = V_oT + 1/2GT^2
    DeltaY = Y_f - Y_i

    V_o = 0
    Y_i = 0

    G = -9.8

    I hope that help.

    It seem you made gravity 9.8 when it should be -9.8 since gravity is going down so it would be negative.
     
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