XPost: sci.math   
   From: relativity@paulba.no   
      
   Den 12.11.2025 22:31, skrev Maciej Woźniak:   
   > On 11/12/2025 9:56 PM, Paul.B.Andersen wrote:   
   >> Den 12.11.2025 18:13, skrev Maciej Woźniak:   
   >>> On 11/11/2025 8:58 PM, Paul.B.Andersen wrote:   
   >>>>   
   >>>> A force is what makes a mass m accelerate at a. F = ma   
   >>>>   
   >>>   
   >>> "A force is what makes a mass m accelerate at a. F = ma"   
   >>> Do you  accelerate on orbit or not?   
   >>>   
   >> According to Newton, yes.   
   >> According to Einstein, no.   
   >   
   > So, according to your mumbling guru - (the second   
   > derivative of  position in time) of an Earth   
   > satellite - is 0. Right, poor trash?   
   >   
      
   According to elementary math:   
   The second derivative of the position of the satellite   
   in the non-rotating Earth centred frame of reference (ECI)   
   is a vector which is pointing towards the centre of the Earth   
   with magnitude v²/r, where v is the satellite's orbital speed   
   and r is the radius of the orbit.   
      
   According to Newton this is the centripetal acceleration   
   of the satellite, a = v²/r.   
      
   But according to Einstein the proper acceleration of the satellite   
   is a = F/m where m is the mass of the satellite and F is the force   
   acting on it. Since no force is acting on an object in free-fall,   
   the proper acceleration of the satellite is zero.   
      
   ----   
      
   A wise person would learn from this, but you won't.   
   Or will you? :-D   
      
   --   
   Paul   
      
   https://paulba.no/   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)