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Homework Help: Finding the max range of a jump on the moon using kinematics

  1. Jun 15, 2011 #1
    1. The problem statement, all variables and given/known data
    A person can jump a maximum horizontal
    distance (by using a 45 ◦
    projectile angle) of
    4 m on Earth.
    The acceleration of gravity is 9.8 m/s
    What would be his maximum range on the
    Moon, where the free-fall acceleration is g
    6 ?
    Answer in units of m.

    2. Relevant equations

    Kinematics equations

    3. The attempt at a solution

    All I can think to do is set kinematics equations for the x and y axis equal to each other by another variable, such as time. This is as far as I can figure out with this problem.
  2. jcsd
  3. Jun 15, 2011 #2


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    hi garcia1! :smile:

    (have a degree: ° and try using the X2 icon just above the Reply box :wink:)

    from the first part, find the speed at which this person can jump

    then use that speed with the Moon's g to find how far he will jump on the Moon …

    what do you get? :smile:
  4. Jun 15, 2011 #3
    24.0304m/s, by using the fact that vf = 0, and then solving for VoY and getting 6.26m/s. I then plugged this into:

    Y = Vy^2 - VoY^2 / (2*-9.81m/s^2 / 6) = 12.01518

    Multiplying by two because I used Vf = 0 at the top of the jump, I got 24.0304m. It was right!!
  5. Jun 16, 2011 #4


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    :biggrin: Woohoo! :biggrin:

    ok, now have you noticed that the range is inversely proportional to the gravity (24/4 = 6)?

    can you prove that, and so avoid all the tedious arithmetic? :wink:
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