Parallelogram of force

Main article: Vector addition

Figure 1: Parallelogram construction for adding vectors

Using a parallelogram to add the forces acting on a particle on a smooth slope. We find, as we'd expect, that the resultant (double headed arrow) force acts down the slope, which will cause the particle to accelerate in that direction.

The parallelogram of forces is a method for solving (or visualizing) the results of applying two forces to an object. When more than two forces are involved, the geometry is no longer parallelogrammatic, but the same principles apply. Forces, being vectors are observed to obey the laws of vector addition, and so the overall (resultant) force due to the application of a number of forces can be found geometrically by drawing vector arrows for each force. For example, see Figure 1. This construction has the same result as moving F₂ so its tail coincides with the head of F₁, and taking the net force as the vector joining the tail of F₁ to the head of F₂. This procedure can be repeated to add F₃ to the resultant F₁ + F₂, and so forth.

See also

• Vector (geometric)
• Net force
• Head to Tails method