1) Resultant force:
The two forces have same magnitude (4 N) but opposite verse, so their resultant is zero:
[tex]R=4 N + (-4 N)= 0 N[/tex]
2) Couple
The two forces have opposite direction and they are applied at a distance d=0.2 m from the center of the square, so they generate a couple equal to the sum of the torques generated by each force:
[tex]\tau= F_1 d_1 + F_2 d_2 = (4 N)(0.2 m)+(4N)(0.2 m)=1.6 N m[/tex]
