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Math Help - Gravity on Jupiter

  1. #1
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    Gravity on Jupiter

    If a rock falls from a height of 20 meters on planet Jupiter, its height H (in meters) after x seconds is approximately:

    H(x) = 20 - 13x^2

    (a) When is the height of the rock 15 meters?

    (b) When does the rock strike the ground?

    NOTE: The question comes from my precalculus book. Chapter title: FUNCTIONS.
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  2. #2
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    Quote Originally Posted by symmetry View Post
    If a rock falls from a height of 20 meters on planet Jupiter, its height H (in meters) after x seconds is approximately:

    H(x) = 20 - 13x^2

    (a) When is the height of the rock 15 meters?

    (b) When does the rock strike the ground?

    NOTE: The question comes from my precalculus book. Chapter title: FUNCTIONS.
    You should be able to do these.

    a) 15 = 20 - 13x^2

    -5 = -13x^2

    x^2 = \frac{5}{13}

    x = \sqrt{\frac{5}{13}}

    b) Same thing only now H(x) = 0. I get x = \sqrt{\frac{20}{13}}

    -Dan
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    ok

    I totally get it.

    So, I needed to REPlACE H(x) with 15 meters for a and 0 for part b to simplify.

    Thanks!
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    Quote Originally Posted by symmetry View Post
    If a rock falls from a height of 20 meters on planet Jupiter, its height H (in meters) after x seconds is approximately:

    H(x) = 20 - 13x^2

    (a) When is the height of the rock 15 meters?

    (b) When does the rock strike the ground?
    It never strikes the ground, Jupiter does not have a surface (as we understand it,
    and certainly has nothing resembling one any where near where the acceleration
    due to gravity is close to 26 m/s^2).

    RonL
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    Forum Admin topsquark's Avatar
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    Quote Originally Posted by CaptainBlack View Post
    It never strikes the ground, Jupiter does not have a surface (as we understand it,
    and certainly has nothing resembling one any where near where the acceleration
    due to gravity is close to 26 m/s^2).

    RonL
    Actually there is some indication that there may either be a diamond core (which seems a bit far-fetched, but possible) or a solid metallic hydrogen core (which I personally think is more likely.) But agreed, we can obviously only speculate at this point.

    -Dan
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