Surface area problem in 3-d calculus

In summary, the conversation discusses finding the area of the surface z = (2/3)(x^(3/2) + y^(3/2)) using double integrals and the formula for the magnitude of dr/du cross dr/dv dS. The person asking for help has correctly set up the integral and is getting different answers, but ultimately discovers that they made an algebraic error.
  • #1
dukefanfromch
2
0

Homework Statement



Find the area of the surface.
The surface z = (2/3)(x^(3/2) + y^(3/2)), 0 </= x </= 1, 0 </= y </= 1

Homework Equations



Double integral over S of the magnitude of dr/du cross dr/dv dS, which equals the double integral over D of the magnitude of dr/du cross dr/dv dA.
(SSs |dz/dx X dz/dy|dS = SS D |dz/dx X dz/dy|dA)

The Attempt at a Solution


_ 1 1
I found the integral to be SS D (1+x+y)^(1/2) dA = SS (1+x+y)^(1/2) dxdy
_ 0 0
but my answer keeps coming out wrong. I might be making a mistake with algebra because I get a lot of different answers when i do it different ways. This is from an NC State Calculus 3 homework assignment, if anyone may have seen this problem before and remember how to do it. Help?
 
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  • #2
dukefanfromch said:

Homework Statement



Find the area of the surface.
The surface z = (2/3)(x^(3/2) + y^(3/2)), 0 </= x </= 1, 0 </= y </= 1

Homework Equations



Double integral over S of the magnitude of dr/du cross dr/dv dS, which equals the double integral over D of the magnitude of dr/du cross dr/dv dA.
(SSs |dz/dx X dz/dy|dS = SS D |dz/dx X dz/dy|dA)

The Attempt at a Solution


_ 1 1
I found the integral to be SS D (1+x+y)^(1/2) dA = SS (1+x+y)^(1/2) dxdy
_ 0 0
but my answer keeps coming out wrong. I might be making a mistake with algebra because I get a lot of different answers when i do it different ways. This is from an NC State Calculus 3 homework assignment, if anyone may have seen this problem before and remember how to do it. Help?

What you have shown is completely correct. Now, how did you do that integration and what answer did you get?
 
  • #3
I got the right answer finally, 1.4066. It was an algebraic error when I was evaluating the integral. Thanks for telling me I was doing it right though, that helped me know it wasn't a mistake in my set-up.
 

1. What is the surface area problem in 3-D calculus?

The surface area problem in 3-D calculus is a mathematical problem that involves finding the total area of a three-dimensional object. It is often used to calculate the surface area of complex shapes, such as curved surfaces and irregular objects.

2. How is the surface area problem in 3-D calculus different from 2-D calculus?

The surface area problem in 3-D calculus is different from 2-D calculus because it involves finding the area of a three-dimensional object, whereas 2-D calculus only deals with two-dimensional shapes. In 3-D calculus, the surface area is calculated by integrating the partial derivatives of the function representing the object's surface.

3. What are some real-world applications of the surface area problem in 3-D calculus?

The surface area problem in 3-D calculus has many real-world applications, such as in engineering, architecture, and physics. For example, it can be used to calculate the surface area of a building's roof, the surface area of a curved water tank, or the surface area of a 3-D model of a molecule in chemistry.

4. What are some common methods used to solve the surface area problem in 3-D calculus?

There are several methods used to solve the surface area problem in 3-D calculus, including the disk method, shell method, and cross-sectional area method. These methods involve breaking down the three-dimensional object into smaller, more manageable shapes and using integration to find the area of each shape and then adding them together to get the total surface area.

5. What are some challenges that may arise when solving the surface area problem in 3-D calculus?

One of the main challenges in solving the surface area problem in 3-D calculus is determining the correct function that represents the object's surface. This can be difficult for complex shapes and may require advanced mathematical techniques. Additionally, the integration process can be time-consuming and prone to errors, so careful attention to detail is necessary for accurate results.

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