Help?

My old friend said once to me that there is an easy way to put your player shoot an object which hits ground after it has been in the air.
Now I can't remember it anymore.

The game is ordinary 2D platformer.

What should I do, if I want my player to throw a bomb towards the reticle? The bomb should "fly" in the air and when it hits the ground, it explodes immediately.

I know how to put my character to shoot bullet towards the sight but the bullet doesn't land on the ground; it continues its flight path.

- Koboltti