Now, when the aircraft will drop the food package, it will obviously travel a parabolic path.
Let the aircraft be flying with the horizontal speed = v m·s−1.
So, the horizontal velocity given to the food package when left will be same = v m·s−1.
The vertical component will be zero i.e. it is coming down by the effect of gravity.
Let us say the vertical height (altitude) of the aircraft = x m.
Let us say the total time taken by the package to reach the ground = t seconds.
So, Initial vertical downward velocity u = 0 m·s−1.
Distance = -x ( Vertical Downward displacement)
Acceleration due to gravity (g) = -10 m·s−2
Time = t seconds
So -x = 1/2 (-10) t2
Cancelling the negative sign, x = 5 * t2
Now in last 6 seconds, package covered the distance of 780 m
So, distance covered in (t-6) seconds = (x - 780) m
Now, again applying the equation-(x-780) = 1/2 (-10) (t-6)2
Cancelling the negative sign, and solving we get
t = 16 seconds
Putting in first equation x = 5 * t2
we get x = 1280 m = 1.28 km (Answer)
Since, it has travelled a horizontal distance of 1000 m before 6 seconds, so this distance has been covered in (16 - 6 = 10 s)
Distance = Speed * Time
1000 = v * 10 (Horizontal component given to food package is same as speed of aircraft)
v = 100 m·s−1 = 360 km/ hr (Answer).