Line integrals of scalar functions practice problems
Line integrals of a scalar function with respect to arc length, ∫_C f ds. 36 problems with worked solutions; in 36 of them every
equation is proved by a computer algebra system.
20 worked problems
Try each one before opening the solution. Every line is labeled with what checked it. How we verify
\[ \int\limits_{0}^{2 \pi} \sqrt{2} \left. x y + z \right|_{\substack{ x=\cos{\left(t \right)}\\ y=\sin{\left(t \right)}\\ z=t }}\, dt = 2 \sqrt{2} \pi^{2} \]
∫ f(r(t)) ‖r′(t)‖ dt.✓ Proved
Answer \( 2 \sqrt{2} \pi^{2} \)
✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
\[ \int\limits_{0}^{2 \pi} \sqrt{2} \left. x + y + z \right|_{\substack{ x=\cos{\left(t \right)}\\ y=\sin{\left(t \right)}\\ z=t }}\, dt = 2 \sqrt{2} \pi^{2} \]
∫ f(r(t)) ‖r′(t)‖ dt.✓ Proved
Answer \( 2 \sqrt{2} \pi^{2} \)
✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
\[ \int\limits_{0}^{1} \left. x^{2} + y^{2} + z \right|_{\substack{ x=t\\ y=2 t\\ z=2 t }} 3\, dt = 8 \]
∫ f(r(t)) ‖r′(t)‖ dt.✓ Proved
Answer \( 8 \)
✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
Evaluate \( \displaystyle \int_C x^{2} + y^{2} + z \, ds \), where \( \displaystyle C \) is the quarter circle of radius 1 in the xy-plane, from (1, 0, 0) to (0, 1, 0).
✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
Evaluate \( \displaystyle \int_C z \, ds \), where \( \displaystyle C \) is the quarter circle of radius 3 in the xy-plane, from (3, 0, 0) to (0, 3, 0).
✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
\[ \int\limits_{0}^{1} \sqrt{2} \left. x + y + z \right|_{\substack{ x=t\\ y=1 - t\\ z=0 }}\, dt = \sqrt{2} \]
∫ f(r(t)) ‖r′(t)‖ dt.✓ Proved
Answer \( \sqrt{2} \)
✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
\[ \int\limits_{0}^{1} \left. x + y + z \right|_{\substack{ x=t\\ y=2 t\\ z=2 t }} 3\, dt = \frac{15}{2} \]
∫ f(r(t)) ‖r′(t)‖ dt.✓ Proved
Answer \( \frac{15}{2} \)
✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
Evaluate \( \displaystyle \int_C x y + z \, ds \), where \( \displaystyle C \) is the quarter circle of radius 3 in the xy-plane, from (3, 0, 0) to (0, 3, 0).
\[ \int\limits_{0}^{\frac{\pi}{2}} \left. x y + z \right|_{\substack{ x=3 \cos{\left(t \right)}\\ y=3 \sin{\left(t \right)}\\ z=0 }} \cdot 3\, dt = \frac{27}{2} \]
∫ f(r(t)) ‖r′(t)‖ dt.✓ Proved
Answer \( \frac{27}{2} \)
✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
\[ \int\limits_{0}^{1} \left. x y + z \right|_{\substack{ x=t\\ y=2 t\\ z=2 t }} 3\, dt = 5 \]
∫ f(r(t)) ‖r′(t)‖ dt.✓ Proved
Answer \( 5 \)
✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
\[ \int\limits_{0}^{2 \pi} \sqrt{2} \left. x + y \right|_{\substack{ x=\cos{\left(t \right)}\\ y=\sin{\left(t \right)}\\ z=t }}\, dt = 0 \]
∫ f(r(t)) ‖r′(t)‖ dt.✓ Proved
Answer \( 0 \)
✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
Evaluate \( \displaystyle \int_C 3 \, ds \), where \( \displaystyle C \) is the quarter circle of radius 2 in the xy-plane, from (2, 0, 0) to (0, 2, 0).
✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
Evaluate \( \displaystyle \int_C x + y \, ds \), where \( \displaystyle C \) is the quarter circle of radius 2 in the xy-plane, from (2, 0, 0) to (0, 2, 0).
✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
\[ \int\limits_{0}^{1} \sqrt{2} \left. x y + z \right|_{\substack{ x=t\\ y=1 - t\\ z=0 }}\, dt = \frac{\sqrt{2}}{6} \]
∫ f(r(t)) ‖r′(t)‖ dt.✓ Proved
Answer \( \frac{\sqrt{2}}{6} \)
✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
Evaluate \( \displaystyle \int_C x + y + z \, ds \), where \( \displaystyle C \) is the quarter circle of radius 3 in the xy-plane, from (3, 0, 0) to (0, 3, 0).
\[ \int\limits_{0}^{\frac{\pi}{2}} \left. x + y + z \right|_{\substack{ x=3 \cos{\left(t \right)}\\ y=3 \sin{\left(t \right)}\\ z=0 }} \cdot 3\, dt = 18 \]
∫ f(r(t)) ‖r′(t)‖ dt.✓ Proved
Answer \( 18 \)
✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
\[ \int\limits_{0}^{1} \left. x + y \right|_{\substack{ x=t\\ y=2 t\\ z=2 t }} 3\, dt = \frac{9}{2} \]
∫ f(r(t)) ‖r′(t)‖ dt.✓ Proved
Answer \( \frac{9}{2} \)
✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify