The query "11 sep 2001 day of the week" functions as a complex noun phrase. The core noun is "day," which is post-modified by the prepositional phrase "of the week" and pre-modified by the specific date "11 sep 2001." This entire construction serves to identify a singular, specific piece of chronological data. The day of the week for September 11, 2001, was a Tuesday.
This determination is verifiable through multiple methods. Standard digital calendars and historical almanacs consistently list the date as a Tuesday. Computationally, the day can be calculated using perpetual calendar algorithms, such as Zeller's congruence or the Doomsday rule. These mathematical formulas take the day (d), month (m), and year (y) as inputs to produce a numerical result corresponding to a specific day of the week, consistently yielding the value for Tuesday for this particular date.
The identification of the day as a Tuesday is a historically significant detail. As a standard business day in the United States, the attacks occurred when the World Trade Center towers, the Pentagon, and other federal buildings were fully occupied. Financial markets were active, and the nation was operating on a normal weekday schedule. This context is crucial for understanding the scale of the immediate human and economic impact of the event, as the timing was targeted to maximize disruption to the nation's civil and financial infrastructure.
