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Homework Help: Placing x-markers to drop water balloon on students

  1. Dec 24, 2013 #1
    1. The problem statement, all variables and given/known data

    You and your roommate plot to drop water balloons on student entering your dorm. your window is 20m above the side walk. You plan is to place an x on the side walk to mark the spot a student must be when you drop the balloon. You note that most student approach the dorm at 2ms^-1. How far from the impact point do you place the x?

    2. Relevant equations


    3. The attempt at a solution

  2. jcsd
  3. Dec 24, 2013 #2
    The first half, where you computed the free falling time, is correct. The second half - where does 2 ms-2 come from?
  4. Dec 24, 2013 #3
    Opps. A slip in the label of unit which had me confuse velocity for acceleration. I'll redo it. Can I assume acceleration is 0ms^-2? I think I could since the walking velocity is constant, acceleration is zero.
  5. Dec 25, 2013 #4
    xf - xi = 2ms^-1 (2.0192751098s) + 0.5(0ms^-2)(2.019275109s)^2 = 4.03855m
  6. Dec 25, 2013 #5
    Good, but you have way too many "significant" figures.
  7. Dec 25, 2013 #6
    rounded off to 4.03m
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