Question

what is inertia?(phy. class 9th)

Answer 1

a property of matter by which it continues in its existing state of rest or uniform motion in a straight line, unless that state is changed by an external force.

Answer 2

The tendency of a substance to retain its state of rest or motion is called Inertia.

                                                              OR

The the property of a substance due to which it continues to move or be in rest is called Inertia .