I did a video (30 fps) of the motion of of a mass suspended vertically by just one spring in one side. This spring is held by a rope connected to a fixed rod, as shown in the picture.
From the bottom to the top of the picture, we see, a bar of aluminium , another mass, a plastic ruler connected to the spring. The spring is connected to the rope on the other ending. Sorry for the bad resolution of the picture.
Then I used the $Tracker$ to plot the motion of the mass - plot of points - tracks points from 20 to 20 frames - and I got some results that I did not expected what puzzles me.
Could anyone explain me the motion of "equlibrium position" - why it goes up and down?
Thanks in advance.