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Math Help - Creating a straight line equation from a logarithm equation?

  1. #1
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    asasdad
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    Creating a straight line equation from a logarithm equation?

    Show that the equation relating the magnetic force kx^n to the component of the moveable magnetís
    component of weight along the incline is mg sin θ = kx^n, where m = 0.05 kg is the mass of each
    magnet, k is a constant, and g = 9.8 m/s2 is the acceleration due to gravity

    Ok so I have a set of values,

    sintheta
    .05
    .1
    .15
    .2
    .25
    .30

    x(cm)
    14.1
    9.8
    8.2
    7
    6.4
    5.6

    The equation that relates them is mgsintheta = kx^n
    now I hit both sides with log
    log (mgsintheta) = nlog(x) + log(k)

    My question is how do I create x and y values that I can plot on a graph. I assume the x(cm) is on my x-axis but I'm confused what goes on my y-axis.

    Is it just log(.5) or is it log((9.8*.05*sin(.5)) for the y values?
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  2. #2
    MHF Contributor

    Joined
    Apr 2005
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    Re: Creating a straight line equation from a logarithm equation?

    Quote Originally Posted by llama View Post
    Show that the equation relating the magnetic force kx^n to the component of the moveable magnetís
    component of weight along the incline is mg sin θ = kx^n, where m = 0.05 kg is the mass of each
    magnet, k is a constant, and g = 9.8 m/s2 is the acceleration due to gravity
    And what is \theta, the angle the incline makes with the horizontal?

    Ok so I have a set of values,

    sintheta
    .05
    .1
    .15
    .2
    .25
    .30

    x(cm)
    14.1
    9.8
    8.2
    7
    6.4
    5.6

    The equation that relates them is mgsintheta = kx^n
    now I hit both sides with log
    log (mgsintheta) = nlog(x) + log(k)

    My question is how do I create x and y values that I can plot on a graph. I assume the x(cm) is on my x-axis but I'm confused what goes on my y-axis.

    Is it just log(.5) or is it log((9.8*.05*sin(.5)) for the y values?
    These are values you got from a lab?
    You want a linear equation of the form y= Ax+ b so take y= log(mgsin(\theta), x= log(x), NOT x, and b= log(k)
    Last edited by HallsofIvy; April 22nd 2013 at 04:16 PM.
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  3. #3
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    Joined
    Apr 2013
    From
    asasdad
    Posts
    10

    Re: Creating a straight line equation from a logarithm equation?

    Right Theta is the incline with the horizontal.

    Sorry I couldn't quite understand the last thing you wrote. It had a bunch of weird characters my computer didn't feel like loading lol

    So I have my y and x axis,

    I find out y value from y=log(mgsintheta) and i find my X values from x=log(x) ?

    and then my slope is N, and my y-intercept is log(k)?
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