Acessna aircraft has a liftoff speed of 120 km/h .
(a) what minimum constant acceleration does the aircraft require if it is to be airborne after a takeoff run of 240 m?
(b) how long does it take the aircraft to become airborne?

The equation for acceleration  is the ff:
2ad = V2^2 V1^2

V1 = 0
V2 = 120 km/h = 33.33 m/s
d = 240

inputting into the equation you get 2.31 m /s^2 as the acceleration

for B use another acceleration equation
a = change in V/ change in time

2.31  = (33.33 - 0) / (t2 - 0)
t2 = 14.43 seconds

Ithink it is 7. 16