The Probert Encyclopaedia of Science & Technology

INERTIA

Inertia is the property of a body that causes it to oppose any change in its velocity, even if the velocity is zero. An object at rest requires a force to make it move, and a moving object requires a force to make it slow down, accelerate, or change direction. Newton called this resistance to a change of velocity inertia. It has been found that the greater the mass of a body, the higher is its inertia.
Research Inertia