Solution

Statement

$2.2.8.$ A person decided to run on a rubber band stretched over two horizontal rollers, the axes of which have no friction. At first glance, it seems impossible: a person cannot transfer momentum to either the band or the rollers, since their total momentum is zero. Does it follow from this that the person will remain in place?

Solution

To push off, one can use the tension of two rubber bands simultaneously. Thus, it will be possible to push off from them, because the tension will prevent them from scrolling (slipping). By deforming both the upper and lower parts of the band together, the runner creates a net external force via the fixed axes of the rollers.