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Homework Help: Simple Harmonic Motion Lab Data Analysis

  1. Nov 17, 2007 #1
    Here is the problem I am having:
    Professor told me to find the spring constant using our slope of the graph.
    Now the graph that I did on the excel went something like this: On the X-axis of the graph was the weight of the hanging mass in Newtons and on the Y-axis of the graph was the elongation in meters.
    I got the slope by adding tread line to my graph.

    last piece of instructions that he gave to figure out the Spring constant was the Hook's Law, which is nothing more than F = -KX, where K is the spring constant and the negative sign just means the force and elongation are in opposite directions.

    Now, I am stuck as to what do I do with the slope that I got from the graph created on the excel. What does my slope represent? What did I just found out when I got that slope? So far I have not been able to find via search engines that how do I actually use this graph and the slope to figure out my slope constant.

    I know I am slow in understanding this elementary physics, but I need help. Hence my user name "Need_Help!!!"

    So, can anyone out there help me out.


    Also, Does anyone out there know what does slope of Graph of the square of the period ( square * square ) versus the hanging mass's slope gives me?

    What is the procedure on how to determine ( from my above graph ( you know the one with the graph of the square of the period versus the hanging mass ) ) and record what portion of the mass of the spring is oscillating along with the hanging mass?


    What does the slope of graph of square of the period ( period * period ) versus the length of the pendulum ) give me?

    Because professor told me that I have to find the acceleration due to gravity, g , from the slop of the graph of square of the period versus the length of the pendulum by using this formula :[tex] T [/tex] = [tex]2\pi[/tex][tex]\sqrt{\frac{L}{g}}[/tex]

    someone please help.
  2. jcsd
  3. Nov 18, 2007 #2

    Shooting Star

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    Homework Helper

    If the graph of a st line is passing through the origin, then the slope is nothing but the value of y/x at every point. If the slope is m, then m=y/x for any point (x,y). Since, you have plotted weight in the x direction and extension in the y direction, then slope = X/F = mod(1/k).
    T=2*pi*sqrt(M/k). This is the eqn for time period in SHM. Can you answer your 2nd Q from this? We get T^2= constant*M. This looks like a st line if you plot M and T^2.

    All of the spring participates in the oscillation, and if the mass of the hanging weights are much greater than the mass of the spring, the latter can be neglected.
    Figure it out from what I have written in the first para.
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