Final answer:
A data warehouse is not a component of a custom Force.com application; instead, custom applications include custom objects, custom tabs, and a default landing page.
Step-by-step explanation:
A component that is NOT part of a custom Force.com application is a data warehouse. Force.com applications typically include elements such as custom objects which store data specific to the application, custom tabs that provide user interfaces for users to interact with the custom objects, and a default landing page that serves as the starting point or home page of the application when a user logs in. A data warehouse, however, is a system used for reporting and data analysis, and is not a built-in component of Force.com custom applications.