"Returnable friction"...

[iacob alex]

....can be considered,the intreplay with inertia,when we keep a continuous variable velocity.

     Usually,on Earth friction is regarded as "lost energy".

     Frictionis a resistance ,met with by a body,moving over another,is a contact energy "scattering" process.

     If we move,or if we work,a fraction of the deployed energy is spread out,with no return...

     If we lay out ("invest") ,our work into inertia (with variable increasing velocity),we can store this labor...and take it back,if and when we need it.

     The essential condition  to store energy into inertia,is to keep a continuous variable velocity.

     Now,the gravity fall is a natural phenomenon,that offers the possibility to play inertia(see the law of fall velocity).

     A convenient and practical form,to store energy,is rotational inertia of a flywheel.

     If a small falling mass   "m", ,is attached to a flywheel with a great mass "M",the natural  "sinking" process is retarded

,but we have a permanent contact with inertia
  (variable velocity).

    It's like we have access to a "returnable friction".

    It seems that,the first step is to realize a more "resistive" gravity fall,between two gravitational levels...

     All the best!  /  Alex