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Homework Help: Time Period of a pendulum

  1. Oct 30, 2009 #1
    1. The problem statement, all variables and given/known data

    A simple pendulum uses a steel wire as the string. The length of this wire is 1.1m at room temperature. If the temperature is increased by 10.8 degrees Celsius, the length of the wire increases by 1.58 mm. What is the change in period of the pendulum?

    2. Relevant equations

    3. The attempt at a solution
    First I converted 1.58mm to meter = .00158m
    I then tried subtracting T initial from T final in order to get the change in period.
    T initial = 2*pi* (sqrt(1.1/9.8)) = 2.10505 sec.
    T final = 2*pi* (sqrt (1.1+.00158))/9.8) = 2.10656 sec.
    getting the change in period to be = .0015 seconds...which is incorrect.
    I don't know of a formula that takes in to consideration the temperature change.
    Please help, I have been trying to figure this out for 5 hrs now.
  2. jcsd
  3. Oct 30, 2009 #2


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    Homework Helper

    Welcome to PF, Roxanne.
    I ran the problem through and got exactly the same answer as you did!
    It sure looks right. Could the computer be wrong? I don't know how you handle situations like this - write out the solution and hand it to your prof?
  4. Oct 31, 2009 #3
    Hmm I'm pretty sure that when you increase temperature actually the period of a pendulum is supposed to get longer.
    Last edited: Oct 31, 2009
  5. Oct 31, 2009 #4
    I figured out why I kept getting the problem wrong. I needed to include more significant figures in my answer. The answer should have been = 0.0015112693 seconds in order for the on-line system to accept it as correct.

    Thank you for your prompt replies.
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