This is a math question, not a physics question.   
      
   When someone writes a math equation involving the "=" symbol, there   
   is no direction. Both sides are equal without any consideration of   
   direction.   
      
   If one needs to consider direction, use "=>" (imply or follow sign)   
      
   [[Mod. note -- This is true.  But equations also have implications   
   based on common usage.  I think it may be easier for beginning students   
   to grasp the usual dynamics of Newton's 2nd law when written as   
      a = F/m   
   (i.e., specify /F/ and /m/ on the RHS, compute /a/ on the LHS), than   
   as   
      F = ma   
   -- jt]]   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)