1. Not finding help here? Sign up for a free 30min 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!

Questions - solving pendulum period of rotation

  1. Dec 5, 2012 #1
    Questions -- solving pendulum period of rotation

    Physical pendulum has a period of rotation gif.gif
    that changes by Changing the temperature.
    According to the above show that the frequency shift of the pendulum would be:
    gif.latex?%5CDelta%20%5Ctau%20=%5CPi%20.gif

    I have 2 questions,first solving the above question
    and the second how Rotation period of the pendulum could be like this?
    gif.gif
     
    Last edited: Dec 5, 2012
  2. jcsd
  3. Dec 5, 2012 #2
    Re: Questions

    please help me az fast as possible
     
  4. Dec 5, 2012 #3

    HallsofIvy

    User Avatar
    Staff Emeritus
    Science Advisor

    Re: Questions

    Your first question is incomplete. How is [itex]\Delta \theta[/itex] defined?

    As for your second question, it is also incomplete. What are "I" and "d"? I can guess that m and g are mass and the acceleration of gravity and possibly that "d" is the length of the pendulum but my guess would be that "I" is moment of inertia but that does not fit here.
     
  5. Dec 5, 2012 #4
    Re: Questions

    my problem is these too,this is the book practice and hasn't explained anything even the professor didnt understand and he asked me to search for it....
     
  6. Dec 5, 2012 #5

    haruspex

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    Re: Questions

    Change in temperature, I would think. And lm must be the linear coefficient of expansion.
    Yes, I as moment of inertia makes sense. If we assume that, and that d is the length of the pendulum from axis to centre of gravity, and we assume the pendulum expands uniformly, then I get the same answer as the book.
     
  7. Dec 6, 2012 #6
    Re: Questions

    could you please tell more about it? and explain it?
     
  8. Dec 6, 2012 #7

    haruspex

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    Re: Questions

    Do you know how to write down the differential equation for a simple pendulum and solve it? You will need a version of it that does not treat the pendulum as a point mass at the end of a massless rod.
     
  9. Dec 6, 2012 #8
    Re: Questions

    I understand what you mean but I do' know how to solve it
     
  10. Dec 6, 2012 #9

    haruspex

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    Re: Questions

    So you can write down the ODE? If so, please post it.
    Are you expected to be able to solve SHM ODEs, or perhaps just expected to recognise them and quote a solution?
     
  11. Dec 6, 2012 #10
    Re: Questions

    sorry what do you mean by ode shm and odes ?
    Im not native really sorry that bother you and put you in trouble :shy:
     
    Last edited: Dec 6, 2012
  12. Dec 6, 2012 #11

    haruspex

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    Re: Questions -- solving pendulum period of rotation

    Apologies. ODE = ordinary differential equation; SHM = simple harmonic motion.
     
  13. Dec 7, 2012 #12
    Re: Questions -- solving pendulum period of rotation

    I know the diffrential equation but not for pendulum.
    and shm if you mean gif.gif its okay,
    I searched and I understand that complex pendulum period of rotation would be like this gif.gif but dont know how to do diffrential equation for it...
     
  14. Dec 7, 2012 #13

    haruspex

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    Re: Questions -- solving pendulum period of rotation

    OK, that should be enough for the question about change in temperature.
    What you need to work out is how a small increase in length (resulting from a change in temperature) will affect I and d, and hence how it will affect the period. Do you understand how to use differentiation for that?
    In the OP, you also said you wanted to know how the complex pendulum formula could be like that. To answer that, I need to walk you through the derivation and solution of the differential equation. OTOH, I get the impression you're not required to be able to do that yet. Please say how you'd like to proceed on that.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Questions - solving pendulum period of rotation
  1. Period of a pendulum . (Replies: 2)

  2. Period of a Pendulum (Replies: 2)

  3. Period of a pendulum (Replies: 2)

  4. Period of a Pendulum (Replies: 3)

Loading...