# Chapter 3Vectors and Vector Calculus

## 3.1 Vector and Scalar Quantities

In Section 2.2.3, we introduced functions that represent physical quantities in engineering analyses, and whose values vary with the values of the associated independent variables in space (*x*, *y*, *z*) in a rectangular coordinate system) and time (*t*). These quantities are called as *scalar quantities*.

There is another group of physical quantities for which not only the magnitude but also the position and the direction are significant and must be represented.. These are called *vector quantities*. Thus, a *speed* of 80 km/h of a moving car is a *scalar* quantity, but a *velocity* of 80 km/h implies that the car is traveling in specific direction on the road at this speed, so that it is a vector quantity. Engineering analyses involving vectorial quantities will require the ...

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