G.MATH
VECTOR INTEGRAL CALCULUS
Piecewise smooth curve example

To get familiar with calculating line integrals of piecewise smooth curves, we shall look at a simple example.
VIDEO LECTURE


MAIN CONCEPTS
The first step is to break up piecewise smooth curve C into smooth curves. Next is to integrate the individual smooth curves independently.
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CONCEPT
Let C be the curve traversing a quarter circle  from  to  in the plane, then moving along the horizontal line from  to  . We will work with a vector field . Our objective is thus to find .

We limit our analysis to a plane because the vector field  is independent of z and has zero k-component and C happens to be on a plane too.

In this situation, we need to split the piecewise smooth curve C into two separate curves . We shall parameterize these individually as

bearing in mind that the interval in which the parameter varies is as equally important as the x, y functions.

We now evaluate  and  independently. For ,

the position vector is

 and ,

and so

and

We now do the same for the other curve . The position vector is  and  and so .


We add these two results to give us the line integral for C, the piecewise smooth curve consisting of the two smooth curves .

All information presentated, less questions and exercises, is original content of Donny, with slight references to various books.
Video courtesy of YouTube.com service.
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