Gravitational Field

Gravitational Field

1. For a point mass M
   Gravitational force on the mass m_o 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