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Homework Help: How much work is done

  1. Mar 22, 2010 #1
    1. The problem statement, all variables and given/known data

    a 2.00 g ice flake is released from the edge of a hemispherical bowl whose radius is 22.0 cm. the Flake-bowl contact is frictionless. How much work is done on the flake by the gravitational force during the flake's descent to the bottom of the bowl?

    2. Relevant equations

    w=fd

    3. The attempt at a solution

    do i use 9.81 m/s^2 as the force?
    and how do i know the distance?
     
  2. jcsd
  3. Mar 22, 2010 #2
    Re: work

    If you were sitting on the edge of a cereal bowl and you slid down to the bottom of the bowl how far vertically would you have fallen? You've been given that.

    9.8 m/s^2 is the acceleration of gravity. You need a force, mass * acceleration.

    Then you've got the only equation you needed.
     
  4. Mar 22, 2010 #3

    rock.freak667

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    Re: work

    What is the distance between the bottom of the hemisphere and the top of the hemisphere?
     
  5. Mar 22, 2010 #4
    Re: work

    Hopefully this helps, it's not too complicated so don't over think it.
     

    Attached Files:

  6. Mar 22, 2010 #5

    rock.freak667

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    Re: work

    I was asking you. The hemisphere is half of a sphere, so the center to any point on the surface is a radius, so what is the height of the sphere?

    (By height, I mean the vertical distance the ice flake travels to the bottom of the sphere)
     
  7. Mar 22, 2010 #6
    Re: work

    The snowflake starts at the edge of a hemispherical bowl so the height is equal to the radius.

    In your case,
    W = mgr

    If there was a full sphere, the height from top to bottom would be the diameter or 2*radius.
     
  8. Mar 22, 2010 #7
    Re: work

    This height is equal to the radius of the hemispherical bowl that is directly given in the question. So in this case,

    W = mgr
     
  9. Mar 22, 2010 #8

    rock.freak667

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    Re: work

    I apologize, I did not see your post before mine. But I was not asking for my clarity, I was asking the OP.
     
  10. Mar 23, 2010 #9
    Re: work

    Oh, I see, your post makes a lot more sense now ; )
    No problem.
     
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