Questions tagged [geometry]
To be used for questions on geometry closely pertaining to physics. Includes differential geometry and Euclidean geometry. Do prefer the more specific tag differential-geometry for questions about differential geometry.
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Rate of change of surface area is acting weird
Preface- I made this situation up. An uniform metal sphere of given mass $M$, is being continuously fed more mass at its centre at the rate $4 \ \text{kg/s}$. If the density stays constant, find the ...
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What is the diameter size of the umbra shadow cone of the Earth when the Moon passes through it on a lunar eclipse?
I am sure this varies given the distance from moon to earth varies, but a range would be sufficient. I am trying to explain to a flat earther how there is not a lunar eclipse every full moon.
My ...
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de Laval nozzle geometry
After doing some research I was not able to find any information on the geometry of the de Laval nozzle. Are there some kind of ratios that the different sections' radii and lengths have to be in? ...
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What is the line of sight distance across the ocean? [closed]
I just watched an experiment where they had a laser at a height of 50 feet (15 metre) above sea level and were able to see it 23 miles (37 km) away at a receiver which was 20 feet (6 metre) above sea ...
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Is there a general solution to all spherical triangles as described by Arnold Sommerfeld?
Arnold Sommerfeld has demonstrated that it is legal to use spherical trigonometry in solving relative velocity compositions. In this work,
https://en.wikisource.org/wiki/Translation:...
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How to (partially) cross-divide 3D vectors? [migrated]
A useful technique for vector cross-product:
It is often stated that there is no way to 3D cross-divide vectors, which is true, with caveats.
If we know that $ \vec{A} \times \vec{B} = \vec{C} $, and ...
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Applications for generalized Lami's theorem
Hello fellow physics enthusiasts! I recently came across with a generalization of Lami's theorem for four coplanar, concurrent and non-collinear forces in static equilibrium. I was wondering if anyone ...
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If we want to apply the formula for torque $= pE\sin\theta$. It is given in the problem that theta~0° [closed]
Why do we take sin theta to be theta only and not as sin0° ie., 0?
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Position of a particle in the plane [closed]
I'm here to ask a really stupid question just to be sure of its answer. My professor gave us an exercise where we have to determine the Lagrangian of a system that is formed by a circular ring of mass ...
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Conception of earth's size based on the width of the observable horizon when standing at sea level and the circumference of the earth
As an aid to conceiving of the size of the earth, using the information that the horizontal (left to right or right to left) width of (not the distance to) the observable horizon when standing at sea ...
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Tensor of inertia
The tensor of inertia of a solid sphere is $I_{ii}=\frac{2}{5}MR^2$ about an axis passing through its CM. Why would the tensor of inertia of each hemisphere about that axis be $I_{ii}=\frac{2}{5}mR^2$,...
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Calculate launch angle of object moving away from view
I'm writing image processing software and my goal here is to take an image of a projectile moving away from the camera and determine the launch angle. What I already know is:
The actual size of the ...
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Discovery of a Formula for Geostationary Orbit Distance: Seeking Expert Feedback [closed]
I’m an amateur enthusiast without a formal academic background in mathematics or science. Recently, I stumbled upon an idea and derived a formula that I believe calculates the distance traveled along ...
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Einstein's notion of "covariant"
In his The Meaning of Relativity, pg. $11-12$, Einstein explains the notion of "covariant" along the following lines:
Consider a point $\mathbf x$ on a straight line $\mathbf x -\mathbf A=\...
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Throwing a ball in the air
When we throw a ball in the air, we know that if we do not throw it too high, then g can be held constant over the trajectory and we can approximate the curve by a parabola. However we also know that ...
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