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Homework Help: Answer Check for kinematic in 2-d

  1. Sep 25, 2008 #1
    1. The problem statement, all variables and given/known data

    In a local bar, a customer slides an empty beer mug down the counter for a refill. The bartender is momentarily distracted and does not see the mug, which slides off the counter and strikes the floor 1.10 m from the base of the counter. The height of the counter is 0.820 m.
    (a) With what velocity did the mug leave the counter?
    correct check mark m/s
    (b) What was the direction of the mug's velocity just before it hit the floor?
    wrong check mark
    Your answer differs from the correct answer by 10% to 100%.° (below the horizontal)

    2. Relevant equations
    I found (a) which is 2.68 m/s

    3. The attempt at a solution

    For b) i used sqrt(2.68^2+2.68^) = 3.79 and did,
    theta = cos^-1(2.68/3.79) which is 45 degrees, which is wrong but since it say below the horizontal axis, will it be -315 degree?
  2. jcsd
  3. Sep 25, 2008 #2
    I got the same for part a but I got something different for the impact angle.

    the impact creates a triangle with x velocity and y velocity at impact. x velocity is constant at 2.68 m/s and I get 4.01 m/s for y velocity. Just finish it and you should get the right answer.
  4. Sep 25, 2008 #3
    thanks alot.. now i gotta figure out why is the y velocity different .. thanks!
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