1. The problem statement, all variables and given/known data It sounds like a simple question but I am wonder what the scalar properties --mean-- with a problem like this http://img560.imageshack.us/img560/274/dotproduct.png [Broken] Uploaded with ImageShack.us Why/how is the it -6 when they are parallel ? I like the idea of mastering the basics and I can't wrap my head around this scalar value . 2. Relevant equations A /dot B ... 3. The attempt at a solution I know how to do the work but I don't understand. I know why 3*2=6 but I am not sure what this -6 scalar thing mean. I have tried to relate it to the shadow illustration and the ideas of work but I am not real owning the idea.