## Fundamentals of Physics Extended (10th Edition)

The velocity of the particle is unchanging so the a = 0 $m/s^2$. SInce F = ma then F must also be equal to zero in all directions. There are three forces so the sum of all of them must equal zero. Adding F1 and F2 we have F12 = -3N i + 11N j - 4N k. Since F12 + F3 = 0 then F3 = 3N i - 11N j + 4N k