Final answer:
The waterfall model's major flaw is its lack of support for iterative design and adjustments to requirements as development progresses, unlike the more flexible spiral design process.
Step-by-step explanation:
The central problem with the waterfall model is that it does not allow for iterative design or changes in requirements that occur during the development process. Specifically, this model is a sequential process, meaning each stage follows the previous one without room for revisiting earlier phases based on user feedback or new insights. This rigidity contrasts with the spiral design process, which includes iteration where designs are prototyped, evaluated, refined, and tested in multiple cycles, allowing for continuous improvement and adaptation to changing requirements.
Drawing from the context of design processes in engineering, the waterfall model's limitations encompass both a lack of iterative design with user feedback and b the inflexibility towards evolving requirements during the development phase.The central problem with the waterfall model is that it does NOT allow for iterative design with user feedback and it does NOT allow for changes in requirements that ensue during development. The waterfall model is a sequential process where each step follows the previous one in a direct sequence without accounting for the iterative nature of design projects. This means that if there are changes in requirements or the need for iterative design with user feedback, the waterfall model becomes inflexible and ineffective.