Ellipsoid Definition and 91 Threads

Another fun question :) Most bbq's are flat or vaguely round shaped. Would it be better to have an ellipsoid oven, so the coals or heater is at one focus and the food at the other ? That is assuming the deep infra red radiation is good at cooking, as opposed to a frying on a hot surface. If it...

Consider the ellipsoid:$$\mathcal{Q} := \{ \mathbf{x} \in \mathbb{R}^3, \ x^2 + a^2(y^2 + z^2) = 1 \}$$We have local coordinates ##\chi^A = (\rho, \phi)## on the ellipsoid surface defined by ##y = \rho \cos{\phi}## and ##z = \rho \sin{\phi}##. First we look for the metric ##\gamma := \phi^{*}...

[ just a fun question :) ] Thinking of the focussing properties of ellipses - If a swimming pool was shaped liked a large half-ellipsoid...and someone dived in at a focus...would the splash then largely appear at the other focus ? In fact would a swimmer at the second focus then be projected up...

Determine the element ##Q_{11}## of the quadrupole tensor for a homogeneously charged rotationally symmetric ellipsoid, $$\rho=\rho_{0}=\text { const. for } \frac{x_{1}^{2}}{a^{2}}+\frac{x_{2}^{2}}{a^{2}}+\frac{x_{3}^{2}}{c^{2}} \leq 1 $$ The formula is $$Q_{i j}=\int \rho(\mathbf{r})\left(3...

I'm told Earth is an oblate spheroid. Is it possible for a planet to be an oblate ellipsoid (equation modified from (x/a)^2 + (y/b)^2 + (z/c)^2 = 1)? What would be the possible consequences, to include "tumbling"?

There is a formula for the potential ##\varphi## outside of a homogenous ellipsoid of density ##\mu## in Landau\begin{align*} \varphi = -\pi \mu abck \int_{\xi}^{\infty} \left(1- \dfrac{x^2}{a^2 + s} + \dfrac{y^2}{b^2 + s} + \dfrac{z^2}{c^2+s} \right) \frac{ds}{R_s} \ \ \ (1) \end{align*}where...

In "An Introduction to Nuclear Physics by W. N. Cottingham, D. A. Greenwood" for the surface area of an oblate ellipsoid, the following equation is written for small values of ε : The book has said this without proof. I found the following formula for the desired shape: No matter how hard I...

I'm looking for a source that fully derives the complete formula for the surface area of a general (triaxial) ellipsoid. I'd prefer a source that has more than just a full derivation, but also has a fair amount of prose discussion on this topic. Some historical context would be nice, as well...

The answer to the primary question in the summary is the first step in seeking an answer to a more complicated question I plan to post in a separate thread later. This more complicated question is a consequence of the thread...

fig one: I just want to know if i am right in attack this problem by this integral: *pi Anyway, i saw this solution: In which it cut beta, don't know why. So i don't know.

I.m not absolutely sure if this comes under physics or maths, so apologies if I've put it in the wrong place. It is well known that if a sphere is exactly enclosed by a cylinder, the area of the curved surface of the cylinder is equal to hat of the sphere. Does this also apply if the cylinder...

I was able to find the equation of an ellipse where its major axis is shifted and rotated off of the x,y, or z axis. However, I could not find anywhere an equation for a spheroid that does not have its axis or revolution along the x,y, or z axis. How might I go about deriving such an...

Homework Statement Find the volume between the planes ##y=0## and ##y=x## and inside the ellipsoid ##\frac{x^2}{a^2} + \frac{y^2}{b^2} + \frac{z^2}{c^2} = 1##The Attempt at a Solution I understand we can approach this problem under the change of variables: $$x=au; y= bv; z=cw$$ Thus we get...

I need to calculate Young's modulus based on deformation of sphere into ellipsoid. I assume the deforming force acting along one axes. Initial dimensions of the object before (sphere) and after (ellipsoid) deformation are known.Does anyone know or familiar with good reference?

Homework Statement Let E be the ellipsoid x^2 + 2xy +5y^ +4z^2 = 1 Find the Volume of E Homework Equations None, just various integration methods. The Attempt at a Solution I know we're not supposed to say 'I don't know where to start' but with this one I really don't. If the best approach...

Homework Statement Calculate ##\int x^2 dV## over an ellipsoid with semi-axes a, b and c along x, y and z. rotating around the z axis with an angular speed ##\omega##. Homework EquationsThe Attempt at a Solution I managed to calculate this in the case when it is not rotating and I got...

Evaluate ∫∫∫ over E, where E is the solid enclosed by the ellipsoid x^2/a^2 + y^2/b^2 + z^2/c^2 = 1. Use the transformation x = au, y = bv, z = cw. I decided to replace x with au, y with bv and z with cw in the ellipsoid. After simplifying, I got u^2 + v^2 + w^2 = 1. What is the next step...

Is there any limit for which we can approximately write the surface area of a prolate ellipsoid to be 4piA*B comparing with the spherical 4piR*R??

Homework Statement Equation of ellipsoid is: ##\frac{x^2}{4} + \frac{y^2}{9} + z^2 = 1## First part of the question, they asked to graph the equation. I have a question about this, I know that ##-1\leq z \leq 1##. So what happens when the constant 1 gets smaller after minusing some value of...

From the last few sentences of the below attached paragraph, when the inertia ellipsoid is prolate, the body cone rolls outside the space cone; when it is oblate, the body cone rolls inside the space cone. Whether the body cone rolls outside or inside the space cone should depend on whether the...

Homework Statement Find the curve that is the intersection of x-y-z>-10 and x2+y2/4+z2/9=36. Homework EquationsThe Attempt at a Solution The best idea I have is to define x as x=y+z-10 and substitute it into the ellipsoid equation to get a function defined by y and z; the trouble is that...

What is the basic matrix form for a uniform (unit) sphere centered at the origin? Given a vector that specifies the radii (1,1,1) == (r1,r2,r3), I would like the matrix that implies no rotation (is it [[1,0,0],[0,1,0],[0,0,1]]?) and covers the rest of the necessary parameters. I am testing...

http://www.colorado.edu/physics/phys3320/phys3320_sp12/AJPPapers/AJP_E&MPapers_030612/Griffiths_ConductingNeedle.pdf I was reading this paper, and was confused by a result in section 2-A. (Heck they even mention they weren't expecting it themselves). The purpose of the paper is to find the...

Use Lagrange multipliers to find $a,b,c$ so that the volume $V=\frac{4\pi}{3}abc$ of an ellipsoid $\frac{x^2}{a^2}+\frac{y^2}{b^2}+\frac{z^2}{c^2}=1$, passing through the point $(1,2,1)$ is as small as possible. I just need to make sure my setup is correct. $\triangledown...

Homework Statement Let ## E ## be the ellipsoid: $$ \frac{x^{2}}{a^{2}}+\frac{y^{2}}{b^{2}}+z^{2}=1 $$ Let ## S ## be the part of the surface of ## E ## defined by: $$ 0 \leq x \leq 1, \ 0 \leq y \leq 1, \ z > 0 $$ Let F be the vector field defined by $$ F=(-y,x,0)$$ A) Explain why ##...

This is another problem I am having difficulty with... I set it up like I've been working the book problems, especially the sphere problems, but can't seem to get the right answer. I feel that I am calculating the radius incorrectly. I know I am supposed to us $${x}^{2}+{y}^{2}={r}^{2}$$ and...

Homework Statement Using Cylindrical coordinates, find the total flux through the surface of the ellipsoid defined by x2 + y2 + ¼z2 = 1 due to an electric field E = xx + yy + zz (bold denoting vectors | x,y,z being the unit vectors) Calculate ∇⋅E and then confirm the Gauss's Law Homework...

Homework Statement [/B] Find the outward flux of the vector field ## \vec F = y^2e^{z^2+y^2} i + x^2 e^{z^2+x^2} j + z^2 e^{x^2+y^2} k## across that part of the ellipsoid $$ x^2 + y^2 + 4z^2 = 8$$ which lies in the region ##0 ≤ z ≤ 1## (Note: The two “horizontal discs” at the top and bottom are...

Hi, I have been referencing this (https://www.physicsforums.com/threads/radius-of-ellipsoid.251321/) previous post to calculate the radius of a Triaxial Ellipsoid (a>b>c), but I'm running into some issues. Let 0 ≤ ϕ ≤ π 0 ≤ θ ≤ 2π and x=r * cos(θ) * sin(ϕ) (1) y=r * sin(θ) * sin(ϕ)...

Homework Statement a,b is constant and s is impact parameter, θ is scattering angle. i know that ψ in the picture is <ψ=(π-θ)/2> Homework Equations differential scattering crossection dσ/dΩ = (s/sinΘ) I ds/dθ I and σ(θ)=∫(dσ/dΩ)dΩ The Attempt at a Solution i guessed, first step is that...

Homework Statement Hi I require to compute the volume of a ellipsoid that is bounded by two planes. The first horizontal (xy) plane is cutting directly along the mid-section of the ellipsoid. The second horizontal plane is at a z = h below the first horizontal plane. The volume of the...

Homework Statement Find volume of the ellipsoid ##x^2 +2(y^2+z^2) \le 10## intersected by the cylinder ##y^2 + z^2 \le 1 ## The Attempt at a Solutionseems like changing to cylindrical coordinates would be best so I have \left\{ \begin{array}{cc} r^2cos\theta + 2r^2sin^2\theta +2z^2 \le 10...

I will state the specifics to this problem if necessary. I need to find the parametric equations for the the tan line at point, P(x1,y1,z1) on the curve formed from paraboloid intersection with ellipsoid. The parametric equations for the level surfaces that make up paraboloid and ellipsoid...

Homework Statement I'm an engineering student, and my professor of the mechanics course gave a homework to my class last week, we were intended to calculate the real shape of the Earth (as an ellipsoid) by taking the centrifugal force in account, using the equation a' = a -wX(wXr). For that...

Homework Statement Using double integrals, calculate the volume of the solid bound by the ellipsoid: x²/a² + y²/b² + z²/c² = 1 2. Relevant data must be done using double integrals The Attempt at a Solution i simply can't find a way to solve this by double integrals, i did with triple...

Homework Statement Hey, I'm doing some physics programming for a game, and could use some general help getting a formula. I'm not great with mathematics/physics, but I know enough to comprehend any feedback. Any help is greatly appreciated! So I have an object free-floating in 3D space at...

I am given a pretty basic ellipsoid: $$\frac{x^2}{16}+\frac{y^2}{9}+\frac{z^2}{1}=1$$ First, for each number t in the interval \(-1\leq{t}\leq{1}\) I need to find the area A(t) of the plane cross-section made by \(z=t\). This I know should be a function of \(t\). After that I have to find the...

Homework Statement Construct a C∞ natural differential structure on the ellipsoid \left\{(x_{1}, x_{2}, x_{3})\in E | \frac{x_{1}^{2}}{a^{2}}+\frac{x_{2}^{2}}{b^{2}}+ \frac{x_{3}^{2}}{c^{2}}=1\right\} Is this diffeomorphic to S2? Explain. Homework Equations Do I need to prove...

I have an ellipsoid representing the Earth (WGS84) and the current location of a spacecraft (somewhere above the surface). I am trying to find a method that allows me to calculate the straight line distance from the point to the surface of the ellipsoid. Any help would be appreciated...

I recently saw a documentary, which claimed that if the Earth rotation slows down the water of the oceans will flood to the north and south because the centripetal force at the equator diminishes. In fact, earth’s radius is about 20 km longer at the equator than at the poles. However, I doubt...

Homework Statement By making two successive simple changes of variables, evaluate: I =\int\int\int x^{2} dxdydz inside the volume of the ellipsoid: \frac{x^{2}}{a^{2}}+\frac{y^{2}}{b^{2}}+\frac{z^{2}}{c^{2}}=R^{2} Homework Equations dxdydz=r^2 Sin(phi) dphi dtheta dr The...

Homework Statement So I keep coming across problems that suggest finding the Volume of an ellipsoid using the volume of a ball ie: Find the volume enclosed by the ellipsoid: (x/a)^2 + (y/b)^2 + (z/c)^2 = 1 by using the fact that the volume of the unit ball in R^3 is 4pi/3...

I am working on a Matlab sim and I need to find the shorted distance of a point to an Elliposid surface. The point is defined as [X,Y,Z]. Elliposid center is defined as [Xc,Yc,Zc] Ellipsoid is defined as A B C E F G H I J (I don't if that's sufficient information for ellipsoid...

Homework Statement Find the point on an given ellipsoid that is the farthest to a given surface.(Distance between point on ellipsoid and surface should be max).Homework Equations ellipsoid: \left(x-3\right)^{2}\over{3}+y^{2}\over{4}+z^{2}\over{5} = 1 surface: 3x+4y^{2}+6z + 6=0 The Attempt...

Homework Statement Let E be the ellipsoid \frac{x^2}{a^2}+\frac{y^2}{b^2}+z^2=1 where a>\sqrt{2} and b>\sqrt{2}. Let S be the part of the surface of E defined by 0\le x\le1, 0\le y\le1, z>0 and let \mathbf{F} be the vector field defined by \mathbf{F}=(-y,x,0). Given that the surface area...

Homework Statement In order to advance on a problem I'm working, I need to covert this ellipsoid from cartesian to spherical coordinates. \frac{x^2}{a^2} +\frac{y^2}{b^2} +\frac{z^2}{c^2} = 1 Homework Equations x^2 +y^2+z^2= \rho ^2 x=\rho sin \phi cos \theta y= \rho sin \phi sin...

Homework Statement a)Evaluate ∫∫∫E dV, where E is the solid enclosed by the ellipsoid x^2/a^2+y^2/b^2+z^2/c^2 =1. Use the transformation x=au, y=bv, z=cw. b)If the solid in the above has density k find the moment of inertia about the z-axis. Homework Equations ∅=phi The Attempt...

This isn't homework or anything, I just want to understand the question better. Homework Statement The Attempt at a Solution I'm honestly not sure where to go with this. Is this an integral problem? As I understand it I'm finding the area of a slice, not a volume of the whole...

I have a matrix D (it happens to be in R^(nxm) where n>>m, but I don't think that is relevant at this point). I also have a vector t in R^n. I am interested in rewriting the set {x | (Dx-t)'(Dx-t) <= c} in standard ellipsoid form: --> {x | (x-z)'E(x-z)<=b} where E is an mxm positive...

In this context, the support mapping of any convex geometry is any point on the geometry which results in the largest dot product to some direction vector. I would appreciate some help in computationally finding the support mapping of an arbitrary ellipsoid (some arbitrary orthonormal basis...