Turning "off" friction by removing the normal force during a free fall

Описание: There is no phyphox and no data acquisition in this video, but of course we can appreciate the fascination of a simple experiment. Here is a little experiment that Christoph did around his Experimental Physics I lecture at RWTH Aachen University (the same lecture that spawned phyphox):

When Christoph drops the plank together with the yellow mass, there is no more normal force between them. Consequently, there is no more friction slowing the motion of the yellow mass.