From: tkoenig@netcologne.de   
      
   Luigi Fortunati  schrieb:   
   > Luigi Fortunati domenica 08/04/2018 alle ore 01:24:36 ha scritto:   
   >> Thomas Koenig mercoled=EC 04/04/2018 alle ore 09:35:02 ha scritto:   
   >>> Well, you have removed most effects of what will happen from consideratio=   
   >>> n; the only major effect left (that I can think of) is viscoelasticity.   
   >>>   
   >>> Rubber can be quite elastic for short deformations; a force applied only   
   >>> for a short time, and then removed, will lead to a smaller deformation   
   >>> than a force applied for a longer time.   
   >>>   
   >>> So, for this, the tread will be deformed a little less, so the vehicle   
   >>> will rise a bit.   
   >>   
   >> Your answer is the exact confirmation of what I expected: the vehicle   
   >> in speed tends to rise a little, that is to weigh less against the   
   >> asphalt, compared to the stationary car.   
   >>   
   >> [[Mod. note -- The vehicle's weight will be unchanged (assuming the   
   >> road to be straight & flat (neither curving-up nor curving-down).   
   >> As Thomas Koenig explained, this *same* weight will lead to a smaller   
   >> tire deformation at high speed.   
   >> -- jt]]   
   >   
   > It is undoubtedly true that the weight of the car in motion is always   
   > the same, but the moving car distributes its weight on a wider surface   
   > of the ground (with respect to the stationary car).   
      
   This is not correct; in fact, the opposite is true.   
      
   > The tread works like a spring and then we can apply Hooke's law to its   
   > compression: the compressed tread of 2 millimeters exerts at its ends a   
   > force *less* than a third, compared to the same tread compressed by 3   
   > millimeters.   
      
   Hooke's "law" is not a law of nature. It is a correlation which   
   is true within certain error limits for materials such as metals   
   below their yield stress.  (And even for steel, it is not quite   
   correct, or the coefficient of resition would be equal to one -   
   a steel ball dropped onto a steel plate would bounce back to the   
   same height, which it does not).   
      
   Hooke's law is false (i.e. does not even begin to describe reality)   
   when applied to viscoelastic materials such as rubber.   
      
   Rubber, due to its viscoelastic nature, exhibits creep - put   
   a constant load on a part made of rubber, and it will exhibit   
   increasing deformation over time.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)