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Homework Help: Determine the maximum tension in the pendulum rod

  1. Mar 19, 2012 #1
    1. The problem statement, all variables and given/known data

    A clock’s pendulum is 60 cm long with a bob at the end of mass 500 g. Determine the maximum tension in the pendulum rod when the bob is

    b) swinging at a speed of 2.4 m/s

    2. Relevant equations

    v^2 / r = ac

    3. The attempt at a solution

    9.8m/s^2 = g

    (2.4)^2 / 0.6 = 9.6m/s^2

    9.8 * 0.5 = 4.9N

    9.6 * 0.5 = 4.8N

    Fnet = 4.9 - 4.8 = 0.1 N

    What am I doing wrong? ._.

    Thank you.

    Okay guys I looked t it from another perspective and ended up wit the right answer.

    I added the force of gravity and the tension going up.

    But here's a small question. Why do we have to add them? Are they not cancelling each other out? Or is it because the pendulum is balanced ? o.o

    So we add both tensions?
    Last edited: Mar 19, 2012
  2. jcsd
  3. Mar 20, 2012 #2


    User Avatar
    Science Advisor
    Homework Helper

    hi nesan! :smile:
    i'm very worried by your last question :redface:

    what did you think the two tensions were? :confused:

    (the acceleration is upward

    Ftotal = ma, so T - mg = ma, ie T = ma + mg)
  4. Mar 20, 2012 #3
    Yup, I got that last night while in bed thinking. Haha xD

    Thank you. :)<3
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