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Homework Help: Math problem

  1. Mar 8, 2008 #1
    I have this math problem for school that I need help with

    A ball is rolling down an inclined plane. The equation I have is y = .165x^2 + .997x + .845 where y is the distance travelled and x is the time taken

    I want to predict the distance it has rolled in 2 days, which I can do

    but what sort of assumptions would i have to make?

    and what are the strengths and limitations for the model?
    for example, a limitation is that when it reaches terminal velocity the model won't work anymore because the model expects the speed to keep increasing

    i dont know anything about physics so i need help
  2. jcsd
  3. Mar 8, 2008 #2


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    You need to provide information about your starting equation. You state that x is time, is it seconds, hours, or days? It makes a difference. Can you tell us where your equation came from?
  4. Mar 8, 2008 #3
    x is time in seconds

    y is distance in metres

    the equation came from the data i got from rolling the ball down the slope. i recorded it using a motion sensor, then i came up with a line of best fit for the data. thats my equation
  5. Mar 8, 2008 #4


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    Why did you post this in the math section (and title it "Math Problem)? None of those question have any thing to do with mathematics (you did the math part when you derived that equation), they have to do with physics.

    I'm going to move this thread to physics homework.
  6. Mar 8, 2008 #5
    thank you. i titled it math problem because its for a math assignment...i don't even do physics

    but it sort of is more like physics
  7. Mar 9, 2008 #6


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    Some more questions:
    Why did you choose to fit to a quadratic?
    How good was your fit?

    What physics can do for you is predict the values of, and give meaning to your coefficients. I am surprised that you would be given this problem without the underling physical model.

    As far as assumptions go, there is an obvious one concerning length of the ramp required to roll for 2 days.
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