This physical_ex is thought as a mean to demonstrate some sorting algorithm(s) for array of numbers. Numbers are visualised with balls. Any two of them can be compared and ordered according to their masses. Compares are made via sophisticated comparing unit. The whole mechanism consists of several similar comparing units and pipes connecting outputs of units involved on earlier step to inputs of units on step that follows. Connections are arranged according to sorting algorithm that is to be demonstrate. Comparing units may be reconnected in other way so that various algorithms could be visualised.

Design development for the comparing unit was a continuous struggle. Thanks to Robin Jamet IC16 contained a 5-day long workshop devoted mainly to this problem. A prototype built there was later reconsidered, redisigned and rebuilt. And finally I am glad to present it for MPE as a functional item. 

Input of this mechanism is 4 balls of different weights that are placed at 4 starting positions. After start of operation balls move to comparing units of the first step and further according to sorting algorithm. 

This physical_ex is expected to make abstract idea of sorting algorithms intuitively obvious to high schoolers.

Disclaimer: I do emphasise that currently only comparing unit is presented. The whole sorting mechanism is still under construction: it is expected to be up before the end of the autumn term.