What physical concept explains why a body in motion tends to stay in motion?

Inertia is the physical concept that explains why a body in motion tends to stay in motion. It refers to the property of an object to resist changes in its state of motion. This means that an object in motion will continue moving at a constant velocity in a straight line unless acted upon by an external force. Essentially, inertia is a manifestation of Newton's first law of motion, also known as the law of inertia.

This concept helps to understand various phenomena in everyday life, such as how passengers in a vehicle feel a jolt when the vehicle suddenly stops; their bodies tend to continue moving forward due to inertia. Thus, inertia is a fundamental principle in physics that clarifies the behavior of moving objects, illustrating the natural tendency of motion to persist unless disrupted.