1. When I see the variable v at some place, how do I know as to whether v is being defined as velocity or speed? On Wikipedia both, velocity and speed, are referring to a formula with v. 2. What is the average velocity of the following: http://img226.imageshack.us/img226/3798/veloc0zt.jpg [Broken] (consider one unit=1s resp. 1m/s and the vector of the velocity is always 0°)? According to my book it must be zero: v[average]=0.5(v[final]+v[initial]). Is the book right?