Vectors are needed for almost all areas of Physics. This is a quick reminder of vector analysis for those who have had one exposure to the area.
Overview
In this lesson, we shall begin with vectors as geometrical objects.
A quick review of a few vector algebra identities will be presented.
With a choice of coordinate system, vectors are described as objects with three components.
We will present a result on change in components of a vector when coordinate axes are changed.
Prerequisites
A first exposure to vector algebra; Dot, cross and triple products.
Components of a vector along coordinate axes.
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Recommended for those who need more details:
- Vector algebra
- Dot and Cross Product of Two vectors Video 1, Video 2
\(\S1\) Vectors as Geometrical Objects
\(\S2\) An Example
\(\S 3\) Vector Algebra Identities
EndNotes
- Mathematical equations representing laws of Physics must be scalar or vector equations (more generally tensor equations), This means that each term in a equation must be an object with same transformation properties.Different terms cannot have different transformation properties. For example, a physical law cannot be represented as a vector = a (non zero) scalar quantity.
- Vectors merely introduced as objects having length and direction, as is done in many school level text, is not a useful concepts.Vectors when equipped with operation of multiplication by a number, addition by parallelogram law and scalar product becomesuseful concept. The definition of mathematical concepts such as Linear Vector Spaces and Inner Product Spaces has roots in the ordinary vectors as introduced at school level.
- The concept of vectors is generalized to tensors and appears in contexts of many symmetry groups.An example is four vectors and tensors that is required in relativistic theories.
References
For a quick review of vector algebra see
Murphy\cite{Murphy} Ch4;
Griffiths\cite{Griffiths-EM} Ch1;
For use of vectors in Physics see
Feynman Lectures Vol-I\cite{Feynman1} Ch 11.