Thursday 4 April 2013

Gravitational Field


Gravitational Field
  1. For a point mass M
    Gravitational force on the mass mo at P



    Gravitational field intensity at P due to M.



     is the unit vector radically inward towards O.

    So, gravitational field lines for a point mass are radically inward straight lines



    e.g., Two point masses B and A each mass M are kept at (0, a)  and (a, 0) respectively.

    Find the gravitational field at (0, 0).



    Gravitational field intensity due to A at origin

    Gravitational field intensity due to B at origin

    Applying principle of superposition, net gravitational field


  2. Spherical shell of mass M, radius R
    1. At a point outside of shell (r > R)



      (Total mass is assumed to be concentrated at the centre)
    2. At a point on the surface (r = R)


    3. At a point inside the shell (r < R)



      No field line exist inside the shell variation of gravitational field (l) versus distance (r) from centre

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