Step 1: Convert km/h into m/s.
Given, radius of the circular path, r=1 km=1000 m.
Speed of the aircraft, v=900 km/h
v=900×10003600m/s=250 m/s
Step 2: Find the centripetal acceleration.
As the centripetal acceleration is given by, ac=v2r
Substituting the value of v and r, we get
ac=250×2501000
ac=62.5 ms−2
We know that acceleration due to gravity, g=9.8 ms−2.
Now, acg=62.59.8=6.38≈6.4⇒ac=6.4g.