A fixed joint is identified by the first digit in the symbol number, which would be?

In pneumatic and hydraulic systems, joints are often categorized using a symbol numbering system for clarity in schematics. The first digit in the symbol number indicates the type of joint being represented. A fixed joint, which is a type of connection that does not allow for movement between the connected elements, is designated by the number "2."

This means that if you encounter a symbol with a "2" as the first digit, it signifies that the joint is fixed, restricting relative motion between the components. Understanding this classification is crucial for interpreting mechanical diagrams and ensuring proper assembly and operation of machinery where such joints are employed.