Plumbers what scientific knowledge do they need to use and how do they use it?

Question

this is important so please describe it as best as you can

thank a lot

Answer 1

Water (and things that float in it) runs downhill.

Answer 2

More about knowing building codes.  Everything they do will get inspected before an occupancy permit can be issued.  other than that Bernoulli's principles.

Answer 3

Plumbers need a basic understanding of hydraulics, even if they do not need to use the numbers  involved.

They need to understand the use of basic tools.

They need to know which products they can use on which materials for unclogging drains, even if they do not know or understand the chemistry involved.  (Different pipe materials have different strengths and different vulnerabilities.)

They need to know  practical amount of pressure, positive and negative (suction) and the strength of materials being worked on.  

All these things are best learned by experience,  an apprenticeship.  Some book knowledge can help but it will not replace constant practice.