Statement I: If three forces $\vec F_1$, $\vec F_2$ and $\vec F_3$ are represented by three sides of a triangle and $\vec F_1 + \vec F_2 = -\vec F_3$, then these three forces are concurrent forces and satisfy the condition for equilibrium.
Statement II: A triangle made up of three forces $\vec F_1$, $\vec F_2$ and $\vec F_3$ as its sides taken in the same order, satisfies the condition for translatory equilibrium.
In the light of the above statements, choose the most appropriate answer from the options given below:
Answer: (A) Both Statement I and Statement II are true.
$\vec F_1 + \vec F_2 = -\vec F_3$ means $\vec F_1 + \vec F_2 + \vec F_3 = 0$. Three forces acting at a point (concurrent) with zero resultant are in equilibrium, so Statement I is true.
Forces forming the sides of a closed triangle taken in order add to zero (triangle law), so the net force is zero: translational equilibrium. Statement II is true.
Solution by Sreeraj P, M.Sc Physics