Evaluating a Surface Integral: A Parallelogram

In summary, the surface integral can be evaluated using the formula \displaystyle \int \int _R f(x(u,v),y(u,v), z(u,v) || r_u \times r_v||dA, where the determinant of the parametric equations is \sqrt 14.
  • #1
bugatti79
794
1

Homework Statement



Evlute the surface integral

Homework Equations



f(x,y,z)=x+y+z where sigma is the parallelogram with parametric equations x=u+v, y=u-v and z=1+2u+v where 0 <=u<=2 and 0<=v<=1.



The Attempt at a Solution



I have no idea how to tackle this. Any suggestions?
 
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  • #2
bugatti79 said:

Homework Statement



Evlute the surface integral

Homework Equations



f(x,y,z)=x+y+z where sigma is the parallelogram with parametric equations x=u+v, y=u-v and z=1+2u+v where 0 <=u<=2 and 0<=v<=1.



The Attempt at a Solution



I have no idea how to tackle this. Any suggestions?

You might begin by studying the material at:

http://tutorial.math.lamar.edu/Classes/CalcIII/SurfaceIntegrals.aspx
 
  • #3
LCKurtz said:
You might begin by studying the material at:

http://tutorial.math.lamar.edu/Classes/CalcIII/SurfaceIntegrals.aspx

I believe we have to use [itex] \displaystyle \int \int _R f(x(u,v),y(u,v), z(u,v) || r_u \times r_v||dA[/itex]

I calculate the magnitude of the determinent to be \sqrt 2 hence

The surface integral becomes

[itex] \displaystyle \sqrt{2} \int_{0}^{1} \int_{0}^{2} (4u+v+1) du dv[/itex]...?
 
  • #4
I agree with everything except the ##\sqrt 2##.
 
  • #5
LCKurtz said:
I agree with everything except the ##\sqrt 2##.

since we have the determinant as 3i+1j-2k and the magnitude is

[itex]\sqrt(3^2+(-2^2)+1)=\sqrt 14[/itex] cheers
 
  • #6
bugatti79 said:
since we have the determinant as 3i+1j-2k and the magnitude is

[itex]\sqrt(3^2+(-2^2)+1)=\sqrt 14[/itex] cheers

The ##\sqrt {14}## is correct, but 3i + j - 2k is not a determinant; it is a vector.
 

FAQ: Evaluating a Surface Integral: A Parallelogram

What is a surface integral?

A surface integral is a mathematical concept used in multivariable calculus to calculate the total flux or flow across a surface. It involves integrating a function over a two-dimensional surface in three-dimensional space.

What is the formula for evaluating a surface integral over a parallelogram?

The formula for evaluating a surface integral over a parallelogram is ∫∫R F(x,y) dA = ∫∫D F(x,y) √(1+g1(u,v)2+g2(u,v)2) dudv, where R is the region of the parallelogram in the xy-plane, D is the corresponding region in the uv-plane, and g1(u,v) and g2(u,v) are the parametric equations of the parallelogram's sides.

How is a surface integral over a parallelogram different from a regular double integral?

A surface integral over a parallelogram is different from a regular double integral because it involves integrating a function over a two-dimensional surface rather than a two-dimensional region in the xy-plane. This means that the bounds and coordinates used in the integral will be different.

What is the purpose of evaluating a surface integral over a parallelogram?

The purpose of evaluating a surface integral over a parallelogram is to calculate the flux or flow across a surface, which can have many real-world applications. For example, it can be used to calculate the amount of fluid passing through a surface or the amount of heat transferred across a surface.

Are there any special techniques for evaluating surface integrals over parallelograms?

Yes, there are special techniques for evaluating surface integrals over parallelograms, such as using parametric equations and the Jacobian matrix to transform the integral into a simpler form. These techniques can make the evaluation process more efficient and accurate.

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