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Questions tagged [geometry]

To be used for questions on geometry closely pertaining to physics. Includes differential geometry and euclidean geometry.

To be used for questions on geometry closely pertaining to physics. Includes differential geometry and euclidean geometry.

1001 questions
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Why are diamond shapes forming from these evenly-spaced lines?

Not sure if this is where I should be posting something like this, but here goes. I wrote a small program today that maps 512 evenly-spaced points on the edge of a circle, and then, iterating over each point, draws a line from the center to that…
Delfino
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4 answers

How far into space does one have to travel to see the entire sphere of earth?

Virgin Galactic will take passengers aboard SpaceShipTwo as high as 65 miles above the surface of the earth. But from this altitude, passengers will only be able to see a certain segment of the curvature of the earth through windows as large as 17…
samthebrand
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Painting with a Pendulum: Would it be possible to graph the pattern?

I intend to try and replicate an experiment that I found online: The idea seems to be: Attach a string to a fixed, overhead object Attach a can of paint to the string Put a hole in the bottom of the can and plug it Pull the can to one side Unplug…
User1974
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Determine the effective radius of a gear?

I'm trying to determine the gear radius using a ruler by $cm$ but I just don't know what to measure: 1- the length from gear center point to the end of the gear tooth ? Or 2- the length from gear center point to the start of the gear tooth ?
Mohammad Fakhrey
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3
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1 answer

Why did staining marks on these paving slabs form geometric shapes?

[edited to add more examples] Along several streets in London I can see paving slabs that have become stained in the middle of the slab with white-ish marks forming different shaped patterns. The staining is permanent, all year round and not…
roblev
  • 671
2
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1 answer

What would the horizon look like on an infinite plane?

What would the horizon look like on an infinite plane? I can imagine the growth of a horizon to be similar to a decreasing exponential function. Where the growth of horizon decreases more as the distance away from it increases. See graph below…
user71793
1
vote
1 answer

Characteristic length of a triangle

I am reading a paper on collision detection in cloth simulation, please help me understanding following lines written in the paper : To check if a point x4 is closer than some thickness h to a triangle x1 x2 x3 with normal n we first check if the…
user2481909
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vote
1 answer

Galvo angle of rotation to distance convertion

I have a galvomotor with a specified maximum rotation of $20^o$, say $\pm10$. It's specified to rotate 1 mechanical degree per $0.5$ V. I shoot a red laser at the scanner mirror, the laser is then reflected to a target located at distance of 175.064…
j.valerio
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What is the geometric viewpoint of different tensors?

Let $V$ be a vector space and $\tilde{V}$ be its dual space. Let $T^{a_1 ... a_n}_{\ \ \ \ \ \ \ \ \ \ \ \ b_1 ... b_m}$ be a type $(n,m)$ tensor. By definition, it is a multlinear map $$T: \tilde{V^n} \times V^m \to\mathbb{R}.$$ It seems like we…
Jbag1212
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What determines the sign of phase dislocations?

I am studying the nonlinear Schrodinger equation $$A_t+iA_{xx}+i|A|^2A=0$$ for $A=ae^{i\theta}$ a complex valued function, with $a,\theta$ real. I am trying to figure out what sets the signs of the phase dislocations, and in particular the frequency…
Nick P
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1 answer

The relationship between abstract geometrical concepts and reality?

In pure geometry points have no parts, lines no breadth and surfaces no thickness, geometrical figures can be exactly congruent. But how do these concepts relate to the physical world. What is the relationship between the laws of geometry and the…
moho
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Calculating angles for tetrahedral molecular geometry

Let's say I have a molecular like CH3F (i.e. fluoromethane), and I'm able to measure the angle (theta) between the C-H bonds. Provided (theta) what is the angle between the C-F bond and the C-H bonds?
Roger Harris
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Is there a formula to solve for chair rail geometry?

Picture a chair with 4 perfectly vertical legs joined at the top by a rail between each pair. The top face of each rail is a perfect 90-degree rectangle. If we lean each leg a few degrees towards the centre, the top face of each rail becomes a…
dcwalker
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Lambert's Problem - "parametrization" of the orbit

A paper regarding Lambert's Problem states the following: When the geometry of the radius vectors is fixed, there is only one free parameter left that wholly defines the transfer time between r1 and r2. In the original formulation, such parameter is…
T.A. Neal
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Geometric Surface-to-volume ratios

Is there any physical or scientific significance for the fact that an inscribed sphere in a regular tetrahedron have exactly the same surface to volume ratio at any size?, (i.e. does it have any use or applications?)
SdogV
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