Application:
If 'n' equal magnitude coplanar forces acting at a point simultaneously with the angle between any two adjacent forces is and keep it in equilibrium then
n =\(\frac{{360}}{\theta }\)
The above forces can be represented by side of a closed regular polygon taken in an order.
Note :
i)Single force cannot keep the particle in equilibrium.
ii)Minimum number of equal forces required to keep the particle in equilibrium is two.
iii) Minimum number of unequal coplanar forces required to keep the particle in equilibrium is three.
iv) Minimum number of equal or unequal non coplanar forces required to keep the particle in equilibrium is four.
Note :
Equilibrium of a body requires not only translational equilibrium (zero net external force) but also rotational equilibrium (zero net external torque) as we are going to read in future topics.