Answer: deposition
Explanation:
Try process of elimination. We know it's not boiling because that is basically water turning into gas. It's not condensation because it's not water which collects as droplets on a cold surface when humid air is in contact with it.
Stop and look to see if anything is coming

let's use first equation of motion to solve this ;
Velocity after 30 seconds = 170 m/s
For every action there is an equal and opposite reaction. Newton's Third Law of Motion.