.....or spring as muscle , at : https://www2.nau.edu/~sll/springs.htm (https://www2.nau.edu/~sll/springs.htm)
If we mount a spring on a ( constant length arm ) pendulum , we have :
https://youtu.be/z6_NRNw88Jw (https://youtu.be/z6_NRNw88Jw)
.....a variable length arm pendulum.
If we mount a spring on a double pendulum...a.s.o.
https://youtu.be/DVr7KnpDAOc (https://youtu.be/DVr7KnpDAOc)
https://youtu.be/PIWbW2co5mY (https://youtu.be/PIWbW2co5mY)
.....can we play a possible "vivid" attachment/"help" of rotational inertia ?
Al_ex