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Homework Help: Rugby Player Collision Question-

  1. Oct 14, 2007 #1
    Rugby Player Collision Question--

    1. The problem statement, all variables and given/known data

    Two rugy players are running towards each other. They are 37 m apart. If one is accelerating from rest at 0.5m/s² and the other was already moving at 3.1 m/s and maintains her speed,

    a) how long before they crunch together?
    b) how fast was the accelerating player going?
    c) how far has each player run?

    2. Relevant equations

    In this situation: The five equations of linear kinematics

    v2 = v1 + a∆t
    ∆d = ½(v2 + v1)∆t
    ∆d = v1∆t + ½a∆t²
    ∆d = v2∆t - ½a∆t²
    v2² = v1² + 2a∆d

    3. The attempt at a solution

    37-d= a(d/v)²/2
    37-d= a(d²/v²)/2
    74-2d= a(d²/v²)......

    And I trailed off from there as I was confused. Now I know you may have to isolate the displacement in this case, however I have not yet encountered a question like this before and it was not clearly explained to me beforehand. Hopefully I'll know what to do through these forums.
  2. jcsd
  3. Oct 15, 2007 #2


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    Staff Emeritus
    Science Advisor

    One travels d and the other travels 37-d.

    They meet at the same time, so find two equations in the two unknowns d and t.
  4. Oct 15, 2007 #3
    I thought it revolved around that, thank you. I used the quadratic formula and found two roots, which was my time for both rugby players, and it went smoothly from there.
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