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How To measure Moon Orbital Velocity ?

  1. Sep 13, 2008 #1
    Im doing a school project where we need to come up with an accurate way to measure the moons orbital velocity with an experiment....

    My plan was to find the radius of the moons orbit, then its period, and based on a distance over time find its velocity. However i realize I am making a serious approximations and takes away from the quality of my measurement.

    Do you know of a better way i can do such a calculation with less error? Also i have 10 weeks to have said task completed.

    All help is appreciated

    thanks,

    Zak
     
  2. jcsd
  3. Sep 14, 2008 #2

    Vanadium 50

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    Why yes, yes I do. But if I were to tell you, wouldn't your grade be based on my work and not yours?

    You are correct that velocity is distance/time. You can easily measure the moon's period, but how are you going to get the distance? So clearly that's not so helpful. You'll need some other relationship. Let me point out that there is a hint in the title of your thread. One word is more important than the others.
     
  4. Sep 14, 2008 #3
    lol yes your right but i was looking for more of a push in the right direction. I could find the distance by using data from past eclipses like Hipparchus did.. then can i say its orbit is a circle and use geometry to get its distance traveled over time? My big question is how could i approach this to get a lower percent deviation? Can i say the moon orbits in a perfect circle and not have a significant impact on my data? In reality my teacher couldnt be bothered as is only a small part of a total project/presentation but it would be nice to have a close estimate instead of being off 1000 m/s.

    is my plan of attack going to have good results ?

    thanks for imput

    zak
     
  5. Sep 14, 2008 #4

    Vanadium 50

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    You're working too hard.

    Why is the moon in orbit? Tackle it from that direction.
     
  6. Sep 28, 2008 #5
    ok its because its in the earths gravitational field. The earth and the moon are attracting each other, the net effect is that the moon is pulled toward earth. Always falling... the reason it doesnt hit is because the moon is constantly moving at a given orbit velocity. this makes the moon always "miss" the earth....

    so do i look at it like the force of attraction= Gm1m2/r*r = centripetal acc ??

    am i looking at it right? my group also found a way were you have a graduated eye piece in a telescope... and measure the relative diameter of the moon over its period seeing its diameter oscillate and based on focal length of lens in telescope determine distance from optics equations....

    are we getting warmer ?? lol

    thanks for imput
     
  7. Sep 28, 2008 #6

    Chronos

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    Lunar laser ranging experiment might be helpful.
     
  8. Sep 29, 2008 #7

    Vanadium 50

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    Well, that's not a correct equation, since you have a force on one side and an acceleration on the other. I'll also point out that it'll work better if you use g instead of G.
     
  9. Feb 8, 2010 #8
    This is probaly way to late but why dont you think about finding the circumference of the the circle and using that as the distance variable in the veloctiy= distance/time. since i know that Vanadium wants you to learn by yourself, im going to let you research how long it takes for the moon to go around the earth. :)
     
  10. Feb 10, 2010 #9

    ideasrule

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    This is obviously necroposting, but I'm curious: all the users responding to the question assumed the OP was trying to compute the Moon's orbital velocity. It seemed to me that the OP wanted to measure it empirically.
     
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