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Homework Help: Golf question

  1. Dec 18, 2014 #1
    1. The problem statement, all variables and given/known data
    http://puu.sh/dzuq5/629a29dd48.png [Broken]

    2. Relevant equations
    x = vo t + ½ a t2
    2 a x= v2 - vo2

    3. The attempt at a solution
    1/4 d = vo t + ½ a t2

    multiply equation by 4,
    d=4 ut+ 2a t2

    so I am thinking answer is 4u, but it is 2u.
    Last edited by a moderator: May 7, 2017
  2. jcsd
  3. Dec 18, 2014 #2


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    Does that mean you think ½ a t2 in the ¼ d case is the same as 2 a t2 (different t ?) in the distance =d case ?
  4. Dec 18, 2014 #3
    no. But I am not sure of the correct way too. so pls help .
  5. Dec 18, 2014 #4


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    Well, if we go through "all variables and given/known data" in "problem statement" and "relevant equations", we see u, d, x, v0, a, t and v.

    In your attempt at solution, you have ¼ d = vo t + ½ a t2 . Correctly, if I assume vo is u .

    You don't use the second relevant equation. Why not? What does it mean ? What is v ?

    All this is for the ¼ d case. What changes for the d case ? And what stays the same ?
  6. Dec 18, 2014 #5


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    Do you know a different equation relating distance, speed and acceleration?
  7. Dec 18, 2014 #6

    rude man

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    Look at this in energy terms instead. It took kinetic energy E to get to d/4, so how much energy is needed to get to d?
    And finally, what is the relation between kinetic energy and speed?
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