solution:
acceleration of the rocket , a = 16 m/s^2
total height , H = 940 m
let the time taken for rocket to stop after acceleration is t
as 16 \times T = 9.8 \times t
t = 1.63 \times T
Now, for height = 950 m
h = 0.5 \times 16 \times T^2 + 0.5 \times 9.8 \times t^2
950 = 0.5 \times 16 \times T^2 + 0.5 \times 9.8 \times(1.63 \times T)^2
solving for T