From: ttt_heg@web.de   
      
   Am Sonntag000001, 01.02.2026 um 14:49 schrieb Paul B. Andersen:   
   > Den 31.01.2026 20:43, skrev Maciej Woźniak:   
   >> On 1/31/2026 8:21 PM, Paul B. Andersen wrote:   
   >   
   >>>   
   >>> How do you think Newton would have answered the following   
   >>> questions?   
   >>> An object with mass m is stationary when t < 0.   
   >>> At the time t = 0 a force F is applied on the body.   
   >>> Would he have said that the body can never accelerate because   
   >>> it's speed is zero?   
   >   
   > No answer, Maciej?   
   >   
   > If you hold a ball in your hand, the speed of the ball   
   > is zero both in its rest frame and in your rest frame.   
      
   We can  actually chose the frame of reference we like.   
      
   Usually we chose to be at rest in respect to ourself or at least in   
   respect to our living room.   
      
   But in fact we ain't that stationary, because the Earth we stand on   
   rotates around it own axis and that axis around the Sun. The entire   
   solar system moves around the center of our home galaxy and that galaxy   
   moves, too.   
      
   So: in effect we 'halt' our own position and declare that to be at rest.   
      
   But given the object we want to throw had the ability to thinkt itself,   
   that object would do the same and regard us as moving.   
      
   > That means that it is impossible for you to throw   
   > the ball because "velocity 'in own rest frame' is   
   > always 0, no acceleration. Sorry, trash."   
      
   No, the own rest frame allows all sorts of movements in respect to that.   
      
   E.g. we could watch a bird flying by in the sky or be could throw a ball.   
      
   Everything moves and we ourself are stationary (by definition).   
      
   That is kind of illusion, but legal.   
   ...   
   >   
   > So I am an idiot because I believe that an "accelerometer"   
   > is an instrument which measures acceleration!  :-D   
      
   Actually a (crude) mechanical accelerometer measures a force, which   
   pushes together a spring. That force is caused by inertia of some sort   
   of test-object inside the device.   
      
   The object has some mass and that resists acceleration and that causes a   
   force upon the spring, which is proportinal to acceleration or elongation.   
      
   ...   
      
   TH   
      
   --- SoupGate-Win32 v1.05   
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