Libraries order items, check out items to patrons, process returned items, and organize items on shelves. What data management solution should a library use to track this information?
a spreadsheet
a database
a flat file
a filing cabinet

Database

Explanation:

only #2 represents an object at rest on a table.

in #1, there is no normal force due to the table; the object is accelerating downward.

in #3, the vertical forces are not balanced; the object is accelerating downward.

in #4, neither the vertical nor the horizontal forces are balanced. the object is accelerating upwards and to the right.

an ironworker standing 30 feet in the air is safe wearing a full body harness that is not tied-off.