Final answer:
The prototyping life cycle is the model in which developers generate functional requirements and physical design specifications simultaneously.
Step-by-step explanation:
The model that developers use to generate functional requirements and physical design specifications simultaneously is the prototyping life cycle.
In this model, prototypes are created and evaluated to understand the strengths and weaknesses of the design, leading to iterative changes and refinements. Each iteration helps in improving the design and meeting the criteria and constraints. This model is advantageous as it allows for continuous improvement, but it requires time and resources for each loop in the process.