Answer:
The centripetal acceleration changed by a factor of 0.5
Explanation:
Given;
first radius of the horizontal circle, r₁ = 500 m
speed of the airplane, v = 150 m/s
second radius of the airplane, r₂ = 1000 m
Centripetal acceleration is given as;

At constant speed, we will have;

a₂ = 0.5a₁
Therefore, the centripetal acceleration changed by a factor of 0.5
There are four fundamental forces. Gravitational is one. Elastic is produced by Electrostatic Force( a different fundamental force!)
Gravity has an infinite range. Elecrotrostatic forces reduce significantly as charges move away small distances but are relatively strongly felt. We feel the forces pulling on us when we stretch rubber. But two large balls side by side will not be significantly attracted by their tiny gravitational forces!