physics.........?

Question

A four-engine jet accelerates down the runway
at 5 m/s2.
If one of the jet engines fails, how much ac-
celeration will the other three produce? An-
swer in units of m/s2.

Answer 1

if it accelerates down means the engines are doing an opposite acceleration to the acceleration due to gravity
the free falling body accelerates by 9.8 m/s^2
if the four engines are working and the plane still with 5 m/s^2 so the engines reduces its free falling acceleration by 9.8 - 5 = 4.8 m/s^ 2
so the acceleration done by each engine is 4.8/4 = 1.2 m/s^2
and 1.2 X 3 = 3.6 which is the acceleration done by the three engines
if one engine fail so the plane will fall by more acceleration which is 9.8 - 3.6 = 6.2 m/s^2
Please say that i am right :)

Answer 2

I'm pretty sure that since f=ma, and f is 3/4 of what it was, the acceleration will also be 3/4 of what it was, or 3/4*5 = 15/4 or 3.75 m/s^2

This, of course, neglects the WEIGHT of the engine that falls. If it is a significant fraction of the weight of the plane, then the other three engines will produce MORE acceleration than 3.75 m/s^2

Answer 3

As I know a jet plane with 4 engines has 2 engines per each wing, thus to prevent spinning and catastrophe you have to turn off one more engine to compensate the failed one. The 2 still working engines will produce deceleration 5/2=2.5 m/s^2