1. 2 rocks sliding on a frictionless surface. Given the speed of both initially (which I can’t remember, this is also a 3D question and I can’t remember what else was given). If the 2 rocks stick together what is the end velocity?

Question

1. 2 rocks sliding on a frictionless surface. Given the speed of both initially (which I can’t remember, this is also a 3D question and I can’t remember what else was given). If the 2 rocks stick together what is the end velocity? 
A block is pushed with a force of 12N. The coefficient of kinetic friction is _____ and it experiences a velocity of _____. What is the horizontal force on the block 
I think this was a 3D projectile motion question