Question

Three forces F1, F2, and F3 acting on a particle are in equilibrium.
a) write an equation to represent the equilibrium of the forces F1,F2 and F3.
b) draw a vector diagram to represent the equation (a).

Answer 1

a) If the particle is in equlibrium, then the vector sum of all forces is zero. Thus, obtain:

$$\mathbf{F}_1+\mathbf{F}_2+\mathbf{F}_3=0$$

b) There are a lot of possible ways to arrange the forces in the way, that their sum is zero. One possible solution is shown on the figure below. Here $\mathbf{F}_1+\mathbf{F}_2=-\mathbf{F}_3$, as the equation above implies.