Vector field dot product integration

In summary: This is something you should definitely check. If the vector field has a potential function, then the value of the integral is the potential function at the end points.
  • #1
Unart
27
0

Homework Statement


Calculate F=∇V, where V(x,y,z)= xye^z, and computer ∫F"dot"ds, where
A)C is any curve from (1,1,0) to (3,e-1)
B)C is a the boundary of the square 0≤x≤1, 0≤y≤1... oriented counterclockwise.

Homework Equations


∫F"dot"ds= ∫F(c(t)"dot"c'(t)


The Attempt at a Solution



So my question is how do I pick a curve from the two dots? And, how is it different from a square?
 
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  • #2
Unart said:

Homework Statement


Calculate F=∇V, where V(x,y,z)= xye^z, and computer ∫F"dot"ds, where
A)C is any curve from (1,1,0) to (3,e-1)
B)C is a the boundary of the square 0≤x≤1, 0≤y≤1... oriented counterclockwise.

Homework Equations


∫F"dot"ds= ∫F(c(t)"dot"c'(t)

The Attempt at a Solution



So my question is how do I pick a curve from the two dots? And, how is it different from a square?

Doesn't the suggestion to use "any curve" suggest that it doesn't matter what curve you use? Is that the case in this problem? What do you know about independence of path and potential functions etc.?
 
Last edited:
  • #3
I know that the V(Q)-V(P) should equal the integral for F dot ds along any path. And that's about it. How to approach it I'm confused...
Do I just, do the subtraction of products of the function? Or, do I have to invent a curve too...

How would I approach the square when the z variable isn't mentioned.

This is my first time doing this.
 
  • #4
Unart said:

Homework Statement


Calculate F=∇V, where V(x,y,z)= xye^z, and computer ∫F"dot"ds, where
A)C is any curve from (1,1,0) to (3,e-1)

That is an obvious typo. Does it mean (3,e,-1) or what?

B)C is a the boundary of the square 0≤x≤1, 0≤y≤1... oriented counterclockwise.

Oriented counterclockwise when viewed from where? Above or below the xy plane? And I suppose z = 0??

Homework Equations


∫F"dot"ds= ∫F(c(t)"dot"c'(t)


The Attempt at a Solution



So my question is how do I pick a curve from the two dots? And, how is it different from a square?

Unart said:
I know that the V(Q)-V(P) should equal the integral for F dot ds along any path.
[If the integral is independent of path] And that's about it. How to approach it I'm confused...
Do I just, do the subtraction of products of the function? Or, do I have to invent a curve too...

How would I approach the square when the z variable isn't mentioned.

This is my first time doing this.

First you have to check whether your integral is independent of path and the vector field has a potential function. What is the test for that? And if it does have a potential function ##\Phi## then, yes, the value of the integral is the difference of ##\Phi## at the end points.
 
  • #5
It does... the function is continuous...
 
  • #6
LCKurtz said:
That is an obvious typo. Does it mean (3,e,-1) or what?
Oriented counterclockwise when viewed from where? Above or below the xy plane? And I suppose z = 0??First you have to check whether your integral is independent of path and the vector field has a potential function. What is the test for that? And if it does have a potential function ##\Phi## then, yes, the value of the integral is the difference of ##\Phi## at the end points.

Unart said:
It does... the function is continuous...

Just because a vector field is continuous doesn't mean it has a potential function. There are theorems about gradients and curls and potential functions. What do they tell you for this problem?

[Edit, added]: Have you had the "fundamental theorem of calculus for line integrals"?$$
\int_P^Q \nabla \Phi \cdot d\vec R=\, \, ?$$
 
Last edited:

Related to Vector field dot product integration

1. What is a vector field dot product?

A vector field dot product is a mathematical operation that combines two vector fields to produce a scalar value. It is also known as the scalar product or the inner product.

2. How is the dot product of two vector fields calculated?

The dot product of two vector fields is calculated by multiplying the magnitudes of the two vectors and then multiplying it by the cosine of the angle between them.

3. What is the significance of the dot product in vector field integration?

The dot product is used in vector field integration to calculate the work done by a vector field on a particle moving along a specific path. It helps to determine the direction of the force acting on the particle and the amount of work done by the force.

4. How is the dot product used in physics and engineering?

The dot product is used in physics and engineering to calculate the work done by a force on an object, the power of a force, and the rate of change of a physical quantity. It is also used in determining the angle between two vectors and the projection of one vector onto another.

5. Can the dot product of two vector fields be negative?

Yes, the dot product of two vector fields can be negative if the angle between them is greater than 90 degrees. This means that the two vectors are pointing in opposite directions, resulting in a negative scalar value.

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