Multivariable Calculus · 免费预览

性质与路径依赖性

线性性、在曲线分段上的可加性以及反向时变号等结构性质,此外还发现:连接同一端点的不同路径可能给出不同的功。

1. The algebra any integral deserves

The algebra any integral deserves

2. Do the endpoints alone determine the work

Do the endpoints alone determine the work

3. What path dependence means physically

What path dependence means physically

4. Choosing parametrizations wisely

Choosing parametrizations wisely

5. The two-road computation

For F=(y,−x)\mathbf{F} = (y, -x) from (1,0)(1,0) to (0,1)(0,1), the quarter circle gives −π/2-\pi/2 and the chord gives −1-1. What is the circulation around the loop they form?

6. Recognizing path dependence

When can you replace a line integral by a simpler path between the same endpoints?

7. Using additivity over pieces

A path runs from A to B with work 33, then B to C with work −5-5. What is the work from A to C along the combined path?

8. Sign under reversal

A curve CC carries scalar line integral 77 against arc length and vector line integral 44. Give the vector line integral along the reversed curve, as a plain number.

9. Field on a chord

For F=(y,−x)\mathbf{F} = (y, -x) on the chord r(t)=(1−t,t)\mathbf{r}(t) = (1-t, t), the velocity is (−1,1)(-1, 1) and the dot product simplifies to a constant. Give that constant, as a plain integer like -1.

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