The benefits and harms of inertia? Give examples.

With inertia, the body retains its speed for some time
Benefit:
Firearms would not work without inertia, the gunpowder explodes, gives a sharp push, and then the bullet flies by inertia.
When playing football, the player hits the ball, the ball flies further by inertia.
Harm:
The car is traveling at high speed, you need to brake sharply, but the car will travel some more distance before stopping.
The plane needs a large landing strip, because even after touching the strip, it will still travel a decent distance.