Questions tagged [distance]
The distance tag has no summary.
487 questions
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A question on the nonrelativistic limit of special relativity [closed]
In special relativity, one typically works in the spacetime manifold with the Minkowski metric:
$$ds^2=-c^2dt^2+d\vec x^2.$$
However, I find it intuitive that in the nonrelativistic limit, if one also ...
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Triangulation, how, by drawing triangles schemes, does one control the error of the measurements? [closed]
I am trying to understand triangulation, especially I am focused on the triangulation Méchain and Delambre achieved in the end of the 18th century, in order to measure the distance between Dunkirk and ...
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Large cosmological distances, and their rate of change, as measured by a specific observer
I’m confused about what a specific observer, comoving with the Hubble flow, would measure as the distance to another comoving observer (galaxy) “far away”. I would’ve thought that this should be the “...
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Cosmic measurements done by distant observers
At the present time, we - as observers comoving with the Hubble flow - measure the value for the Hubble constant to about 70 km/s/Mpc and the distance to the our particle horizon as 46,5 Gly. Now ...
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Relation between chordal distance and geodesic distance
The relation between the chordal distance, $u$ and the geodesic distance $d$ is given in D'Hoker and Freedman at the bottom of page 53. They say,
The chordal distance, is given by $u=\zeta^{-1}-1$. ...
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Work Done By Non-Conservative Forces Formula
Consider any non-conservative force, say friction, since the force is path dependent will the work done formula be altered accordingly. The formula for work done is $$W=\vec{F} \cdot \vec{s}\tag{1}$$
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Light travel distance and comoving distance in the Big Crunch scenario
I'm aware that the Big Crunch is practically ruled out, but I need it to ask my question. Imagine, that we live at the cosmic time of the reversal of the expansion, precisely when it stops. At the ...
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Can a moving fluid be considered as a rigid body?
Suppose, there is a fluid inside a container and the container itself is moving with a constant velocity'v'. Since, the velocity of each and every particle of the liquid will be same, their relative ...
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Wigner's Friend distance in MWI
In Wigner's Friend let's say that upon observing the dead cat, he would move 5 meters forward, while if he sees a live cat, he would move 5 meters backwards.
In MWI, there is no collapse and we have ...
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Is there any quantity/unit that represent Mass $\times$ Velocity $\times$ Distance?
I don't know, it seems like Mass $\times$ Velocity $\times$ Distance should represent something important in Physics. Like more mass = more energy, more velocity = more energy, more distance travel = ...
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Wondering about ancient methods of estimating the relative planetary distances
Regarding https://physics.stackexchange.com/a/156155/349202 and estimating with geometry the relative distance of Venus to the sun prior to the Venus transit of 1769, I follow the logic of @viktor-...
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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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Why do objects with greater length feel heavier - and how to calculate perceived weight?
Consider this situation:
As part of some training, you are asked to pull an object that is 100 feet long, weighing approximately 218 pounds across a distance of 310 feet (fire hose across concrete if ...
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Why does the line element expression contain only second order differential terms? [duplicate]
The general expression of the line element $ds^2$ is $$ds^2 = g_{ij}dX^{i}dX^{j},$$ where $g_{ij}$ is an element of the metric tensor.
Is there a rigorous proof of why there are no terms in the ...
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Are comoving distances time-independent?
A comoving reference frame expands along with the universe, factoring out the effect of the Hubble expansion. Suppose a galaxy has a redshift $z = 1$ and its comoving distance DM is $11 \,\mathrm{Gly} ...
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Can distance traveled by a body be zero?
I had seen a teacher saying on YouTube that we must note that distance traveled can not be zero then I searched for the same on net and surely some sources say same e.g. the below link
https://byjus....
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Clarification on Representing Distances and Trajectories in Minkowski Spacetime
In the context of Minkowski spacetime, where the metric has a signature of (-, +, +, +), the $x-t$ plane (spacetime diagram) is commonly used to visualize events and their evolution in both space and ...
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How small can we measure space? [closed]
I got this question after looking into transcendental numbers and I noticed how there are some distinctions that should be made from numbers and reality especially in measurement of length for example ...
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Question about light and distance
If we see into the past with light and distance travelling so we can’t see things how they are currently, only how they were in the past; and James Webb took a photo from the beginning of the universe ...
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Given a distance, and velocity as a function of time, how do I find the time taken to travel the distance? [closed]
Given the velocity of a particle as a function of time V(t), and a distance between two points on a straight line (from point A to point B), I would like to find the time it will take the particle to ...
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Proof that a scalar field invariant under rotations only depends on norm
Let $f: \mathbb{R}^3 \rightarrow \mathbb{R}$ be a real valued scalar field and $\mathbf{r}\in\mathbb{R}^3$ a vector with $r = \sqrt{\mathbf{r}\cdot\mathbf{r} }$ its norm. Let's say that $f$ is ...
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Why decreasing the distance between a parallel plate capacitor increases the electric field? Wouldn't it remain the same? $\sigma/\epsilon_0 $? [closed]
I have been learning capacitors and came across the formula for the capacitance of a parallel plate capacitor. In it capacitance is inversely proportional to the distance between the plates because ...
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How does the definition of a rigid body imply constant distance from the center of mass?
Let there be a system of N point-particles in 3D space, this system is a rigid body. The general definition of a rigid body is $ \mid r_{i}-r_{j} \mid$=constant $\forall i,j$
In one of the books I was ...
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How can we accurately tell distances of celestial bodies when considering superluminal expansion [closed]
If parts of the universe are moving away from each other faster than the speed of light relative to my position in space, how can we accurately tell the age or distance of other celestial bodies ...
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How can we calculate distance of Light? [closed]
Say I am using torch , and I want to calculate distance of light it travelled if I put it upwards , how can I calculate the distance of light ?
