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Homework Help: Pendulum swing angle

  1. Oct 30, 2012 #1
    Greetings Physics adorers!

    I was wondering if somebody could please check my work for the problem below.

    A pendulum with a length 2m has a velocity of 3 m/s at its lowest point. What is the largest angle it creates relative to the horizontal as it swings. Hint: use energy conservation.

    Here is my work
    mgh=mv^2/2,,,,,,,,,,h=0.459 m,,,,,,,,,cos(angle) = h/r=0.459/2,,,,,,,,,,,angle=76.7 degree

    Please let me know if it is correct. If it is wrong, please give suggestions on how I should correct.

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

    2. Relevant equations

    3. The attempt at a solution

    Attached Files:

  2. jcsd
  3. Oct 31, 2012 #2
    The value of h is ok.

    But note that cos(angle) = (r - h)/r
  4. Oct 31, 2012 #3
    Thank you for your response!

    But I am not sure that I understand what you mean
  5. Oct 31, 2012 #4
    Refer to the diagram attached.

    Attached Files:

  6. Oct 31, 2012 #5
    Thank you for the diagram! so cos (angle)= (2-.459)/(2)

    = about 39.60 degrees?
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