Vectors can be used to represent a number of things in engineering a couple being forces and currents.
A vector is used to represent something that has both a magnitude and direction. This could be a force that has a magnitude and the direction it is acting or it could be a current where the magnitude is the current level and the direction represents the angle it forms with other currents in that system.
A simple example being a tug of war taking place between two equally matched teams who are pulling in directly opposite directions. In this case there will be little if any overall movement. But should one member drop out in a team the opposing team would be able to exert more force and eventually pull them over the line towards them.
Mathematically the overall effect in such a system can be worked out by a number of means but just by drawng the lines to scale and at the correct angles to each other each vector will have x and y co-ordinates. By adding these all together you can find the net effect x and y coordinates.
By dragging the red and blue dots in this tool to represent the direction and magnitude of two forces you can see the how when added together they give the coordinates of the resultant vector.
