La pressione

The concept of pressure should be easy to understand; despite that, I’ve found frequent misunderstandings in students, teachers, and books. Is this quantity related to interaction or to the state of a system? Is it a vector, or scalar (or tensor) quantity? How can I understand Venturi’s effect? Many sentences used to explain Stevin’s law can be, in fact, misleading. What is “weight” in common understanding? – Here I’m giving a few suggestions for teaching.