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Find translational Ke Rotational Ke

  1. Dec 9, 2006 #1
    1. The problem statement, all variables and given/known data

    A basketball weighs 500grams or (.5 kg) it has a radius of 10cm (.10 m) and is rolling at 2.0 m/s. Find translational Ke Rotational Ke Translational momentum and Rotational momentum.


    2. Relevant equations
    translational ke= 1/2mv^2
    rotational ke = 1/2Iw^2 ( I am unsure of what inertia equation to use for a basketball)
    Translational momentum= mv^2
    rotational ke = iw
    3. The attempt at a solution

    Translational ke = 1/2 mv^2= .5(.5kg)(2.0m/s)^2= 1 J
    I think I know how to do the equations I just dont know what equation to use for the rotational inertia for a basketball, if someone could help me on that. Thanks :redface:
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Dec 9, 2006 #2

    Andrew Mason

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    I think you mean L = angular momentum = [itex]I\omega[/itex]
    The moment of inertia of a solid or hollow sphere is a calculus problem. It works out to [itex]\frac{2}{5}MR^2[/itex] for a solid sphere and [itex]\frac{2}{3}MR^2[/itex] for a hollow sphere (see the Hyperphysics site). Which one would you use?

    How do you determine the rotational speed from the translational speed? ie. how long does it take the ball to roll 360 degrees or [itex]2\pi[/itex] radians?

    AM
     
  4. Dec 9, 2006 #3

    radou

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