Newton's first law of motion:
an object resist a change in their state of motion in a straight line unless compelled to change that state by an applied force.

all obj. resist a change in their state of motion.the tendency of undisturbed objects to stayat rest or to keep moving with the same velocity is called inertia.this is y ,the 1st law of motion is known as law of inertia.
1 3 1
Tendency of an object to continue its state of rest or motion untill and unless some external force is acted on it

1 5 1