Discuss whether the waterfall model is appropriate for each of the following software projects or not. If not, suggest a better model and provide justifications for your choice.

Project 1: a software team were asked to develop a new mobile app for blind people. The team is not sure about the best form of interaction between the users and the app.

Project 2: a software team were asked to add new functions to an existing human resource management system.

Project 3: a software team were asked to develop a new software in a short period of time. The team is confident that there will be many changes in requirements throughout the project.