1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook