Answer:
F = 19530 [N]
Explanation:
In order to solve this problem we must make a free body diagram and observe the forces acting on the plane.
The cruising speed is taken as a constant speed, i.e. there is no acceleration. Therefore, a zero-equal sum of forces on the X-axis can be performed in order to find the air resistance force.
In the attached schema we can see the free body diagram of these forces.
[tex]F_{t} =19530[N]\\F_{t} - F_{A} = 0\\F_{A} = F_{t} \\F_{A} = 19530[N][/tex]
We can say that the moment the cruising velocity develops, the air resistance force is equal to the force developed by the turbines of the plane.