Fun! Throwing a Ball

A ball is thrown straight up, from 3 m above the ground, with a velocity of 14 m/s. When does it hit the ground? (ignore air resistance, gravity is 9.8 m/s/s)

In your solution, be sure to mention all assumptions you have made about this system/your model for tackling this problem.  Is there any piece(s) of information missing you need to know? How do you know what you don't know? (known knowns, known unknowns, unknown unknowns ....)