Answer:
The answer is D (It reduced his average
force.)
Answer:0.69
Explanation:
Coefficient of kinetic friction=f/R=61.8/90=0.69
The basic unit of mass in the International System of Units. or SI, is D. gram.
Given that,
Initial velocity of the airplane = 66 m/s
Distance = 560 m
Final velocity of the airplane = 0 (stops)
To find,
Acceleration of the airplane.
Solution,
Let us consider that a is the acceleration of the airplane. We can find it using third equation of motion as follows :

Therefore, the acceleration of the airplane is 
I would say B. hope it helps