if a system of coplanar forces is in equilibrium, then their algebraic sum is zero

if a system of coplanar forces is in equilibrium, then the algebraic sum of their moments about any point in their plane is zero

the algebraic sum of the moments of any two forces about any point is equal to moment of theiwesultant about the same point

positive and negative couples can be balanced

mass

velocity

acceleration

force

three forces acting at a point will be in equilibrium

three forces acting at a point can be represented by a triangle, each side being proportional to force

if three forces acting upon a patticle are represented in magnitude and direction by the sides of a triangle, taken in order, they will be in equilibrium

if three forces acting at a point are in equilibrium, each force is proportional to the sine of the angle between the other two

these forces are equal

the lines of action of these forces meet in a point

the lines of action of these forces are parallel

(b) & (c)

reducing the problem of kinetics to equivalent statics problem

determining stresses in the truss

stability of floating bodies

designing safe structures.