Class 1. Construction and destruction of substance-fields
The first class of standards includes transformation methods based on completion and destruction of substance-field models. For instance, an incomplete model of two substances should be introduced a field to ensure interaction between them. If the interaction is harmful, it can be destroyed by introducing a separating substance. The transformation selection depends on the limitations provided in the problem statement.
The standards of this class apply to the following types of problem models:
a substance is available but it is unknown how to act upon it;
two substances are available but there is no interaction between them;
two substances are available, and there is a harmful interaction between them.
To move a heavy train, the locomotive needs to exert a high effort. In principle, its power is enough for this but an issue occurs: the drivers skid on the rails. It means that we have two substances – a wheel and a rail – and a combined (useful and harmful) interaction between them.
According to standard 1.2.1., a third substance should be placed between the interacting substances.
What kind of substance is that?
It should be solid, should ensure high friction, should be easy to feed under the wheels, i.e. It should be loose or liquid. Another important requirement is to be cheap. Regular sand satisfies these requirements quite well, it is fed under the wheels starting from the first locomotives and to the present day.