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I dont know how to graph these pendulum things

  1. Dec 4, 2011 #1
    1. The problem statement, all variables and given/known data
    with frequency as the dependent variable, plot graphs of frequency versus
    (i)Amplitude, for a length of cm and a constant mass
    (ii)mass, for a length of 100cm and constant amplitude
    (iii)length, for a constant amplitude and constant mass.



    2. Relevant equations

    i think i got one for length but not for the others

    (iii)L=g/(4π^2f^2)
    (ii)?
    (i)?

    3. The attempt at a solution
    (iii)
    L=9.8/(4π^2(0.10)^2=24.8 cm
    L=9.8/(4π^2(0.20)^2=6.2 cm
    L=9.8/(4π^2(0.30)^2=2.7 cm
    L=9.8/(4π^2(0.40)^2=1.55 cm
    L=9.8/(4π^2(0.50)^2=0.99 cm

    i did this from 0.10 Hz - 1 Hz
    i took the answers and plotted them on the graph

    (ii)??

    (i)??
     
  2. jcsd
  3. Dec 5, 2011 #2

    Delphi51

    User Avatar
    Homework Helper

    Welcome to PF!

    The question doesn't ask you to find any formulas, though you probably can find them from the graphs. For (i) you would have to swing your pendulum through a small amplitude, perhaps 1 cm, and time 20 or so swings to find the frequency. That's one point on your frequency vs amplitude graph. Repeat with a larger amplitude, say 2 cm, and see what the frequency is. You'll need at least 5 points to make a decent graph.
     
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