what is inertia class 9th

Inertia is a property of matter by which it remains at rest or in uniform motion in the same straight line unless acted upon by some external force. It is one of the three laws of motion discovered by Sir Isaac Newton. The inability of a body to change its state of rest or uniform motion in a straight line by itself is called inertia. Inertia can be divided into three types: inertia of rest, inertia of motion, and inertia of direction. Inertia of rest is the tendency of a body to oppose any change in its state of rest, while inertia of motion is the tendency of a body to oppose any change in its state of uniform motion. For example, when a bus suddenly starts moving forward, the passengers in the bus fall backward due to inertia of rest. On the other hand, when a fast-moving bus stops suddenly, the passengers fall forward due to inertia of motion. The mass of a body is the measure of its inertia, and the more the mass, the more the inertia.