Inertia is the tendency of an object to resist any change in its motion. It is a fundamental property of matter and explains why objects at rest tend to stay at rest and objects in motion tend to stay in motion, unless acted upon by an external force. Inertia gets its name from the Latin word for idleness or laziness, which describes an object's natural tendency to do nothing or maintain its state of motion unless compelled to change by a force.

1. CONCEPTOF INERTIA