Final answer:
A projectile launched at 200 f(t)/sec stays in the air twice as long as one launched at 100 f(t)/sec.
Step-by-step explanation:
The time of flight for a projectile is determined by the vertical motion. A projectile launched at 200 f(t)/sec stays in the air twice as long as one launched at 100 f(t)/sec. This is because the time of flight is linearly proportional to the initial velocity in the y direction. So, if the initial velocity is doubled, the time of flight will also be doubled.