Why learn about vector addition?

In physics, talking about the “net” of some quantity means you are interested in the sum total of all the individual contributions of that quantity. For example, when we begin to discuss energy and talk about the net work done on an object, we want to know the sum of the work done by all the forces acting on an object. But two of the most important problems in introductory-level physics we be solving for the net force acting on an object and the net field at a point in space. Because both forces and fields are vector quantities, asking for the net force or net field means that we need to work a vector addition problems. In fact, we will spend much of this course working vector addition problems in one form or another, whether they ask for the net displacement of an object or the total momentum of a system of particles. To succeed in introductory-level physics, you must be good at adding vectors.

Fortunately, we have already set up most of the machinery we will use to add vectors together. As you will see, there is a process for adding vectors that revolves around breaking vectors up into components. Once we know the components of our vectors, adding them together is relatively simple.