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Homework Help: Work done in a Gravitational Feild of a Hemisphere

  1. Apr 11, 2008 #1
    The problem concerns with the work done by the Gravitational Feild force exerted on a mass 'm' kept on the center of the base of a hemisphere of mass "M" radius "R".

    The way I did it was, first I found the Center of Mass of the hemisphere which is 3R/8. Next I used the concept => Work done= -Potential Energy.

    PE=-8GMm/3R

    So Work done would be= 8GMm/3R

    Work done by Gravitational Feild force is -8GMm/3R

    But the book says the answer is -3GMm/2R

    Where am I wrong . Please Help!
     
  2. jcsd
  3. Apr 12, 2008 #2

    pam

    User Avatar

    Your first formula only applies to a full sphere.
    Your method is wrong.
     
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