Answer:
We need to add 9 N in the direction of F(1)
Explanation:
We know that in equilibrium the total force is equal to zero, so we have:
[tex]F_{total}=F_{1}+F_{2}+F_{3}=0[/tex]
F(1) is 12 N
F(2) is 21 N in the opposite direction
F(3) is the additional force.
Then, using these values into the total force equation we have:
[tex]12-21+F_{3}=0[/tex]
[tex]-9+F_{3}=0[/tex]
[tex]F_{3}=9\: N[/tex]
Therefore, we need to add 9 N in the direction of F(1)
I hope it helps you!
