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taking the natural lof a circular motion equation watch

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    I've got this formula:

    v=(GM/r)^1/2

    where v=velocity
    G=gravitational constant and M is the mass of the sun.

    the question states: by taking the natural logs of both sides rearrange the equation in the form of y=mx+c, identify the gradient and y intercept.

    then it goes on to say draw a graph of ln(v) against ln(r) and estimate the mass of the Sun.

    im assuming the gradient would have been the mass of the sun, but i have no idea how to rearrange the equation to get that, ive tried many ways then tried to see if i got the mass of the sun and it didnt work, any suggestions?

    thanks in advance
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    equation of the line is

    ln v= -0.5ln r + 0.5 ln GM
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    (Original post by SdotK)
    I've got this formula:

    v=(GM/r)^1/2

    where v=velocity
    G=gravitational constant and M is the mass of the sun.

    the question states: by taking the natural logs of both sides rearrange the equation in the form of y=mx+c, identify the gradient and y intercept.

    then it goes on to say draw a graph of ln(v) against ln(r) and estimate the mass of the Sun.

    im assuming the gradient would have been the mass of the sun, but i have no idea how to rearrange the equation to get that, ive tried many ways then tried to see if i got the mass of the sun and it didnt work, any suggestions?

    thanks in advance
    Just outa interest, ru doing physics/engineering at QMUL ?
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    nope, how comes?
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    (Original post by equinox3o0o)
    equation of the line is

    ln v= -0.5ln r + 0.5 ln GM
    that was one of the things i got buy, isnt ln(r) meant to be x? in terms of y =mx +c
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    y = ln v
    m = -0.5
    x = ln r
    +c = 0.5ln GM
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    yeah that makes sense, so you meant to put in values for r and v, cause i have a table as well which tells me the distance and speed of each planet from the sun, put set of those in and u can find M, right?
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    yep yep
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    nice one, i appriciate that. thanks alot.
 
 
 
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