From: poutnik4REMOVEnntp@CAPITALSgmail.com   
      
   >>   
   >> Have you considered the option you are mistaken ?   
   >>   
   >> The mass starts to push the string and vice versa initially with   
   >>  zero force, allowing for the mass full 1 g acceleration.   
   >   
   > How is it possible that the mass pushes the spring with zero force?   
      
   Well, for real spring, some nonzero force is needed to accelerate   
    the spring of a nonzero mass. But for idealised spring, the force   
    F=k * x by the Hook's law, where x is deviation from rest   
    position.   
      
      
   >   
   > Can a spring be contracted without applying any force?   
      
   How do you understand the word initial ? The only force needed us   
    to cause  acceleration of nonzero mass of the spring.   
      
   >> As the spring is contracting both acting and reacting forces increase   
   >> and the mass acceleration decreases.   
      
   > How is it possible that the initial acceleration of the mass can   
   > decrease if initially both the speed and the acceleration are equal to   
   > zero?   
      
   If you just release an apple you have been holding, the initial   
    speed us zero, but initial acceleration is g.   
   As it gets speed, the acceleration is decreasing due increasing   
    air drag.   
      
   >   
   > When we "lean" the mass on the spring, they are both still and the   
   > acceleration can only increase.   
   >   
   False. Think a little bit.   
   The gravity is not disturbed by the spring yet, the initial state   
    is like a free fall, with small deviation of accelerating the   
    spring.   
      
   The acceleration (it's norm) is decreasing to the zero point, when   
    spring force equals m.g.   
      
      
      
   --   
   Libor Striz aka Poutnik ( a pilgrim/wanderer/wayfarer)   
      
      
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