This PSSC film made in 1960 is one of the finest physics films ever made. All students should see it at some point in their studies. See the article '"Frames of Reference" revisited' by Alistair Steyn ...
The observed motion of a point depends on the motion of the observer. Consider point P on the robotic arm shown below. Three GIFs are shown below the provide the view of the motion of point P as seen ...