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: 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.

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