D mentality:
Inertia \In*er"ti*a\, n. [L., idleness, fr. iners idle. See
Inert.]
1. (Physics) That property of matter by which it tends when
at rest to remain so, and when in motion to continue in
motion, and in the same straight line or direction, unless
acted on by some external force; -- sometimes called vis
inerti[ae].