Ajet plane is cruising at 310 m/s when suddenly the pilot turns the engines up to full throttle. after traveling 4.0 km , the jet is moving with a speed of 400 m/s.

For this problem, we would be using the formula: Vf^2 = Vi^2 + 2ad 
where:
Vf = 400m/s 
Vi = 300m/s 
a = ? 
d = 4.0km 
= 4000m 

400^2 = 300^2 + 2a4000 
a = [ 160000 - 90000 ] / 8000 
a = 8.75m/s^2 
rounding it off to 2 significant figures, will give us 8.8 m/s^2.

A., d., and f i think