If an object on which forces are acting is held at rest then the resultant of these forces must be zero.
F1 + F2 + F3 = 0
Consider three forces, F1 , F2 and F3
If the vectors arrow are drawn end-to-end, if they form a closed triangle, then the resultant of the three forces is zero.
The sine rule can then be used to find an unknown force provided all the angles and the magnitude of two of the forces are known. Alternatively, the forces can be resolved into horizontal and vertical forces.
The vector sum of the horizontal forces must be zero. The vector sum of the vertical forces must be zero.
Vertically, F1 = F2sinθ + F3sinα
Horizontally, F2cosθ = F3cosα
A vector triangle can be drawn to represent three coplanar forces if the lines of action of their forces pass through a single point.
The imaginary point P can be considered to be in equilibrium.
F1 + F2 + F3 = 0
Consider three forces, F1 , F2 and F3
If the vectors arrow are drawn end-to-end, if they form a closed triangle, then the resultant of the three forces is zero.
The sine rule can then be used to find an unknown force provided all the angles and the magnitude of two of the forces are known. Alternatively, the forces can be resolved into horizontal and vertical forces.
The vector sum of the horizontal forces must be zero. The vector sum of the vertical forces must be zero.
Vertically, F1 = F2sinθ + F3sinα
Horizontally, F2cosθ = F3cosα
A vector triangle can be drawn to represent three coplanar forces if the lines of action of their forces pass through a single point.
The imaginary point P can be considered to be in equilibrium.