Having hard time applying oop

I'm trying to make throwable projectiles right now, I have a few types in my mind currently, grenade, that explodes on collision, and a knife that teleports the player to it's location on collision. I made a base projectile "class" right now, which is basically a rock that can be thrown by players projectile launcher node. I'm having a hard time understanding what would be the best way to make a child of that "class" with custom behaviour, like exploding or teleporting the player.