Section 16.2 : Line Integrals - Part I
For problems 1 – 10 evaluate the given line integral. Follow the direction of \(C\) as given in the problem statement.
- Evaluate \( \displaystyle \int\limits_{C}{{3y\,ds}}\) where \(C\) is the portion of \(x = 9 - {y^2}\) from \(y = - 1\) and \(y = 2\).
- Evaluate \( \displaystyle \int\limits_{C}{{\sqrt x + 2xy\,ds}}\) where \(C\) is the line segment from \(\left( {7,3} \right)\) to \(\left( {0,6} \right)\).
- Evaluate \( \displaystyle \int\limits_{C}{{{y^2} - 10xy\,ds}}\) where \(C\) is the left half of the circle centered at the origin of radius 6 with counter clockwise rotation.
- Evaluate \( \displaystyle \int\limits_{C}{{{x^2} - 2y\,ds}}\) where \(C\) is given by \(\vec r\left( t \right) = \left\langle {4{t^4},{t^4}} \right\rangle \) for \( - 1 \le t \le 0\).
- Evaluate \( \displaystyle \int\limits_{C}{{{z^3} - 4x + 2y\,ds}}\) where \(C\) is the line segment from \(\left( {2,4, - 1} \right)\) to \(\left( {1, - 1,0} \right)\).
- 6. Evaluate \( \displaystyle \int\limits_{C}{{x + 12xz\,ds}}\) where \(C\) is given by \(\displaystyle \vec r\left( t \right) = \left\langle {t,\frac{1}{2}{t^2},\frac{1}{4}{t^4}} \right\rangle \) for \( - 2 \le t \le 1\).
- Evaluate \( \displaystyle \int\limits_{C}{{{z^3}\left( {x + 7} \right) - 2y\,ds}}\) where \(C\) is the circle centered at the origin of radius 1 centered on the \(x\)-axis at \(x = - 3\) . See the sketches below for the direction.

- Evaluate \( \displaystyle \int\limits_{C}{{6x\,ds}}\) where \(C\) is the portion of \(y = 3 + {x^2}\) from \(x = - 2\) to \(x = 0\) followed by the portion of \(y = 3 - {x^2}\) form \(x = 0\) to \(x = 2\) which in turn is followed by the line segment from \(\left( {2, - 1} \right)\) to \(\left( { - 1, - 2} \right)\). See the sketch below for the direction.

- Evaluate \( \displaystyle \int\limits_{C}{{2 - xy\,ds}}\) where \(C\) is the upper half of the circle centered at the origin of radius 1 with the clockwise rotation followed by the line segment form \(\left( {1,0} \right)\) to \(\left( {3,0} \right)\) which in turn is followed by the lower half of the circle centered at the origin of radius 3 with the clockwise rotation. See the sketch below for the direction.

- Evaluate \( \displaystyle \int\limits_{C}{{3xy + {{\left( {x - 1} \right)}^2}\,ds}}\) where \(C\) is the triangle with vertices \(\left( {0,3} \right)\), \(\left( {6,0} \right)\) and \(\left( {0,0} \right)\) with the clockwise rotation.
- Evaluate \( \displaystyle \int\limits_{C}{{{x^5}\,ds}}\) for each of the following curves.
- \(C\) is the line segment from \(\left( { - 1,3} \right)\) to \(\left( {0,0} \right)\) followed by the line segment from \(\left( {0,0} \right)\) to \(\left( {0,4} \right)\).
- \(C\) is the portion of \(y = 4 - {x^4}\) from \(x = - 1\) to \(x = 0\).
- Evaluate \( \displaystyle \int\limits_{C}{{3x - 6y\,ds}}\) for each of the following curves.
- \(C\) is the line segment from \(\left( {6,0} \right)\) to \(\left( {0,3} \right)\) followed by the line segment from \(\left( {0,3} \right)\) to \(\left( {6,6} \right)\).
- \(C\) is the line segment from \(\left( {6,0} \right)\) to \(\left( {6,6} \right)\).
- Evaluate \( \displaystyle \int\limits_{C}{{{y^2} - 3z + 2\,ds}}\) for each of the following curves.
- \(C\) is the line segment from \(\left( {1,0,4} \right)\) to \(\left( {2, - 1,1} \right)\).
- \(C\) is the line segment from \(\left( {2, - 1,1} \right)\) to \(\left( {1,0,4} \right)\).