## Chapter 3

## Vectors in Physics. Velocity and Acceleration as Vectors

We started the last chapter by stressing the importance of two fundamental concepts in mechanics, namely velocity and acceleration. To make a beginning we confined ourselves to one dimensional motion in which they act like scalar quantities. That narrow view was justified in order to focus on the notion that *v* is obtained by taking the time derivative of x, and *a* is obtained by taking the time derivative of v.

We shall now take a broader view of velocity and acceleration and recognize them as vector quantities. Without this appreciation Newton's Second Law of Motion will remain misunderstood. Many of the misconceptions that prevail among students, and even in some text books, ...