It keeps things going

INERTIA

Newton’s first law describes this property that resists changes in motion—whether an object is at rest or moving steadily.

The clue "It keeps things going" plays on inertia’s definition—the tendency of an object to stay in motion (or at rest) unless acted upon. While it might first make you think of energy or momentum, the word "inertia" fits because it’s the force that maintains movement, not creates it. The phrasing is a bit sneaky since we usually associate "keeping things going" with active effort, but inertia does it passively by resisting change. Think of a spinning top that keeps going until friction stops it—that’s inertia in action.