Calculating Volume using triple integrals

In summary: I'm not sure where you're going with this, but it sounds like you might need to do a different integral in order to get the correct answer.
  • #1
amooo
4
0

Homework Statement



please help me in determining the volume of the solid bounded by

y^2 = 4x
x^2 = 4y
y = 3
x + y =3
z = x - y

i need to use triple integrals

Homework Equations



v = v1 + V2 + V3

The Attempt at a Solution



V1 = triple integral of dz dy dx
 
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  • #2
"v= v1+ V3+ V3" makes no sense if you don't tell us what V2 and V3 are!
Have you done anything at all on this? To start with have you graphed the first 4 equations?
 
  • #3
yes i have plotted the graph. and have determind the limits to be used

i have also calculated the triple integral for dz dy dx,
V1 = triple integral of dz dy dx

now i have to calculate V2 =triple integral of dy dz dx
and V3 = triple integral of dx dz dy

i want to know whether i have to change the limits of these integrals or i should continue with the limits i used for calculating V1

I m new to this so please guide
 
  • #4
V1 will give you the volume of the region, and so will V2 and V3. You don't need to add them together, and it should be the case that V1 = V2 = V3.

Inasmuch as each integral uses a different order of integration, your limits of integration are going to be different for each iterated integral.

Does the problem ask you to calculate all three of these iterated integrals? If not, the only purpose in doing this is as a check on your work.
 
  • #5
Thanks Mark for the input

How do i calculate limits for V2 and V3... any hint for this

al;so if u can refer me some tutorial ...id be grateful .

m able to solve the probs...but the idea is still not that clear to me

Thanks
 
  • #6
How did you find the limits of integration for your first integral? What did you get for these limits of integration?
 
  • #7
a friend of mine helped a bit...but i m not sure for the next 2

also i don't know how to get limits from graph.

my limits for first attempt are

0 - (x-y) for z
(3-x) - (2 sqrt x ) for y
1 - 2 for x
 
  • #8
Are you sure that this is all of the given information on the solid region?
y^2 = 4x
x^2 = 4y
y = 3
x + y =3
z = x - y

You have four "cylinders" that act as vertical walls, and you have one plane, z = x - y, that is either the top or bottom. It seems to me you need one more plane to bound the other end.

I haven't worked this out, but the limits you showed for the integral in the order dz dy dx doesn't seem to match the region, and so shouldn't produce the correct value.
 

Related to Calculating Volume using triple integrals

1. How do you set up a triple integral to calculate volume?

To set up a triple integral for volume calculation, you need to identify the bounds for each variable (x, y, z) and the integrand function. The bounds are determined by the shape and dimensions of the region you are finding the volume for. The triple integral is then written as ∭f(x,y,z) dV, where dV represents the infinitesimal volume element.

2. What is the difference between cylindrical and spherical coordinates in triple integrals for volume?

In cylindrical coordinates, the integral is expressed as ∭f(r,θ,z) r dz dr dθ, where r is the distance from the origin, θ is the angle from the positive x-axis, and z is the height. In spherical coordinates, the integral is written as ∭f(ρ,θ,φ) ρ² sinφ dρ dθ dφ, where ρ is the distance from the origin, θ is the angle from the positive z-axis, and φ is the angle from the positive x-axis in the xy-plane. Spherical coordinates are useful for calculating volume for objects with spherical symmetry, while cylindrical coordinates are useful for objects with cylindrical symmetry.

3. How do you determine the bounds for a triple integral in volume calculation?

The bounds for a triple integral depend on the shape and dimensions of the region you are finding the volume for. To determine the bounds, you can use graphs, equations, or other geometric methods. It is important to carefully consider the orientation of the region and the order of integration to accurately set up the integral.

4. Can a triple integral be used to calculate the volume of irregular shapes?

Yes, a triple integral can be used to calculate the volume of irregular shapes. By setting up the integral with appropriate bounds and integrand function, the volume of any 3D object can be calculated using triple integrals. This is one of the advantages of using triple integrals over other methods of volume calculation, such as using cross-sectional areas.

5. How is the concept of triple integrals used in real-world applications?

Triple integrals are used in various fields such as physics, engineering, and economics to calculate volumes, masses, moments of inertia, and other physical quantities. They are also used in computer graphics and 3D modeling to determine the volume of complex shapes. Additionally, triple integrals are used in probability and statistics to calculate the probability of an event occurring in a 3D space.

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