There are three answers, the impulse is equal to the change in momentum of the system. The dimensions of these quantities are the same, namely mass times velocity. You can think of impulse as kind of the "net effect" that a force has in changing the state of motion of a system.
Until the object starts to move, the static coefficient of friction must be used since the object is at rest initially. If the horizontal force is large enough to overcome the friction force and the object accelerates, we switch to the kinetic coefficient.
The total downward force in the -y direction is the weight plus the applied 26N:
Fy=mg-26N = 5*-9.81-26 = -75.05N
The maximum friction force here is the magnitude of this force times the static coefficient of friction. This force will point in the opposite direction as an applied horizontal force, no matter which way it points (non conservative forces tend to oppose motion in all directions)
Ff=75.05N*1.03=77.3N
Note this is greater than the applied horizontal x-directed force of 26N. This means the answer is 26N of friction force acting on the object. Why not the full 77.3N? Because that is the maximum amount you can oppose along the x-direction before the object starts to move. But since we are only applying 26N, that is all the friction force pushes back with. This is a statement of Newton's 3rd Law of equal and opposite actions. If the object pushed back with the full 77.3N in this case it would accelerate backward (F=ma), since there would be a net force on the object (77.3N - 26N = 51.3N) This obviously doesn't happen!
Trial and error
scientific laws and theories are proven by experimental data and large bodies of evidence.
Given the following choices;
A) less than your true weight, mg.
B) equal to your true weight, mg.
C) more than your true weight, mg.
D) could be more or less than your true weight, mg, depending on the value of the speed.
The answer is; C
This is due to G-force. These are the perception of the weight of an object that is accelerating against gravity. We experience 1 g force on the surface of the earth because the ground exerts an upward exertion against gravity preventing as from falling to the center of the earth.