Time of Flight
The time of flight is twice the time to reach the maximum height,
t_{max}.
Since the time to reach maximum height is 
t_{max} 
= 
 v_{y}(0)
 
a_{y}


The time of flight is 
t_{flight} 
= 
2t_{max} 
= 
2v_{y}(0)
 
a_{y}


= 
2 v_{o} sinθ
 
g


The time of flight is determined solely by the initial yvelocity and
g. Motion along x is irrelevant!
Three balls are launched straight up in the air. The ratio of their
initial speeds is 1:2:3, in the order red:green:blue. What is the ratio of
their times of flight, in the same order?
 1:2:3
 1:4:9
 It depends on the ratio of their masses