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Homework Help: Pendulum Period change due to gravitational force change

  1. Mar 3, 2012 #1

    I was wondering how to go about a pendulum problem, basically if we have a clock pendulum that oscillates with period 2s unaffected; if we add a large mass on the floor, so that the pendulum experiences some small extra gravitational force towards the floor.

    Now I have determined this force and therefore the extra vertical acceleration due to this added floor mass but I now have to determine how this affects the period.

    So provided I know the extra vertical acceleration, how do I determine the effect this has on the period?

    Thanks guys!
  2. jcsd
  3. Mar 3, 2012 #2
    I misread the problem. Comment deleted.
    Last edited: Mar 3, 2012
  4. Mar 3, 2012 #3
    The period of a pendulum for small oscillation is

    P = 2*pi*sqrt(l/g)

    where l is pendulum length and g is acceleration of gravity.
  5. Mar 3, 2012 #4
    So based on the fact that the length doesn't change it is safe to assume that period is inversely proportional to the square root of the acceleration and so it's just a case of using the new acceleration and the initial 'g' acceleration to find the difference in the periods.

    I think this is most probably the way to go about the problem; though correct me if I'm wrong.

    Thanks for the help!
  6. Mar 3, 2012 #5
    I suggest you do a few rough calculations first.Think of the largest mass you could concievably put on the floor,work out how this would change the value of g and then work out whether a simple pendulum would be sensitive enough to detect the extremely small change of time period that this added mass would bring about.
  7. Mar 6, 2012 #6
    Ahh I've only just seen your comment Dadface, clever idea; I "think" i've got the problem solved so I'll try doing that to see if my answer is reasonable.

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