Questions tagged [distance]
The distance tag has no usage guidance.
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Question on minimum distance between two projectiles, considering drag force [closed]
The following was a question posed in a recent test series:
What would the intended solution be to such a question? Are there any defining features that could be used to simplify the problem or is ...
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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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About the connection between distance in Hilbert space and fidelity
I have the feeling that there is a direct relationship between the distance in Hilbert space and the fidelity (similarity) between quantum states.
short version : the distance between two quantum ...
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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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How to deal with square root of negative number when calculating spacetime interval?
I was reading Hartle's Gravity: An Introduction to Einstein's General Relativity and I was doing an exercise from page 57 that asks me to use the metric $\Delta s^2=-(c\Delta t)^2+\Delta x^2$ ...
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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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Observable universe
What does observable universe mean? I saw your graphs in proper and comoving distances. An hypothetical object that emitted light at the Big Bang (after recombination: cosmological time $t=0$ and ...
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I have confusion between the concept of distance and displacement [closed]
I can't understand that why do we say that distance is a scaler quantity and displacement is a vector quantity?
Let me give some examples:
$1)$ Shyam is travelling from New Delhi to Mumbai. Now ...
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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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Inverse problem for geodesic
If I know the expressions for geodesic distance between any points $x$ and $y$:
$$L=L(x^\mu,y^\nu) \ .$$
How do I find the metric of the corresponding space?
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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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The correct dimensional formula for distance travelled in $n$th second? [closed]
I have read other similar questions on this site (including The dimensional formula of distance travelled in $n$th second with the same name), but it does not specifically answer what I was looking ...
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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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Does the distance between two objects of mass not matter when measuring strength of gravity in one-dimensional space?
From all that I have heard about Newton's Law of Universal Gravity, one fact, which I find quite interesting, is that the distance between the two objects of mass is squared and not cubed due to our ...
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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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Speed is equal to distance divided by time but is this correct?
In this study https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9784821/, the distance the punch travelled from start to impact is 0.49 meters and the time taken from start of punch (that's it, they define ...
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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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Average distance travelled by particle points placed uniformly at random in a sphere with speed $||v||$ and direction uniformly random?
I would like to compute the average distance travelled by particle points at constant speed $v>0$ with uniformly-distributed directions and placed uniformly at random inside a hollow sphere of ...
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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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Schutz description of Galilean invariance of interval
In B. Schutz's textbook "A First Course in General Relativity", there is a sentence on page 172 discussing Galilean relativity and how the distance between events is invariant in coordinate ...
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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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Arc length between configurations in the "mass distance"
In classical Lagrangian mechanics, the mass $M$ is a Riemannian metric on the configuration space $Q$.
Does the "arc length" of a path $\gamma : [0, 1] \to Q$,
$$
\int_0^1 {\lVert{\gamma'(t)}...
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Terminology: Is it correct to refer to the spacetime interval as "absolute distance?"
...Because it's Lorentz-invariant.
Different inertial frames observe different distances, durations, and simultaneity. They even report a different time of day on their wristwatch. But everyone in any ...
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Question about light and distance
If we see into the past with light and distance travelling so we can’t see things how they are currently, only how they were in the past; and James Webb took a photo from the beginning of the universe ...
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Are there any forces that are inversely proportional to the fourth power of the distance involved?
As I humbly asked on Astronomy SE, I was wondering if there any forces or similar phenomena that scale inversely proportionally to the fourth power of the distance.
There are plenty of things that ...
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Given a distance, and velocity as a function of time, how do I find the time taken to travel the distance? [closed]
Given the velocity of a particle as a function of time V(t), and a distance between two points on a straight line (from point A to point B), I would like to find the time it will take the particle to ...
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From infinitesimal interval invariance to finite interval invariance in SR
In Landau and Lifshitz's The Classical Theory of Fields, on page 5 about interval invariance between different frames, it reads
Thus, $$ds^2=ds'^2,\tag{2.6}$$ and from the equality of the ...
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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 is the distance between two objects is squared in the definition of Gravitational Force? [duplicate]
In the definition of the Newton's Law of Universal Gravitation, the gravitational force between two bodies is directly proportional to the product of masses of the objects and inversely proportional ...
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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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Which experimental setup replicating Michelson-Morley experiment had the longest path of light?
After the Michelson-Morley (MM) experiment many scientists performed similar experiments using the original MM experimental setup, or different derivative experimental setups employing lasers and ...
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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 to determine whether an object is a point object?
I know that we can consider an object as point object, if its size is negligible as compared to distance traveled by it in reasonable amount of time. But in my book Ncert there is questions which asks ...
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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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Where does the negative signature case come from in the Pythagorean derivation of distances in spacetime?
I am reading Why does $E=mc^2$ (and why should we care?) by Brian Cox and Jeff Forshaw. I want to understand these three sentences
(from page 76/77):
Once we follow Occam and make these two ...
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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 ?
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What symbol is used for 'proper distance'? [closed]
Proper time and proper space are generally defined as what an observer would measure in their own rest frame. If $\tau$ is a commonly used symbol for the proper time, what is the corresponding symbol ...
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I need a ship at rest to accelerate under preferably constant acceleration/deceleration to arrive at rest at an object 55 AU away [duplicate]
I'm working on the story and I need help with the plot point. Assume that the energy needed for constant acceleration is not a problem. And there's no need to complicate this with outside forces.
I ...
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Need clarification/input on a curvature dilemma
Even though I said I'd never waste this much energy arguing with a flat earther, I have a dilemma and need input.
I'm in the Vancouver, Canada area. I've been shown a picture that the person claims is ...
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Definite integral that give distance between two moving particles
I have two particles $P_1$ and $P_2$ and I know how their coordinates change against time $(x_1(t)$, $y_1(t))$ and $(x_2(t)$, $y_2(t))$
I can easily get distance $L$ between them as
$$L(t)=\sqrt{{(x_2(...
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If two opposing equal forces act on an object, how does one calculate the energy exerted? [duplicate]
If energy exerted is a function of distance and force, the object would not move in this case. But would energy not still be exerted?
Simplified the example for sake of clarity; but specifically ...
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Simple distance calculation in General Relativity
So imagine a spacetime with the Schwarzschild metric:
$$ds^2=-c^2\left(1-\dfrac{2GM}{c^2r}\right)dt\otimes dt+\dfrac{1}{\left(1-\dfrac{2GM}{c^2r}\right)}dr\otimes dr+r^2\left(d\theta\otimes d\theta+\...
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Can a big enough Giant travel many lightyears in just a few seconds? [closed]
We, as humans, given our height and size, view the world from the same general perspective. An ant, on the other hand, will understand the same world in a completely different way, given how limited ...
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What distance (comoving, proper, light travel time distance) does the cosmic distance ladder actually give us?
In most material I can find on the cosmic distance ladder for a lay-level reader like myself, it never seems to explicitly say what distance its talking about.
There is the proper distance when the ...
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Is the unit $m^2$ for area size ambiguous? [closed]
In normal case, we use $m^2$ to represent the size of an area - the product of two distance whose corresponding quantities are perpendicular. But it can also be simply the square of one distance, such ...
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Why is relative velocity not defined on curved manifolds, is relative distance also not defined?
I understand that relative velocity is not defined on curved manifolds because you are comparing vectors from different tangent spaces. Lets say body A is moving vith velocity $v_A$ and body B with ...
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Explain the equation
Can someone explain me this equation. This is braking distance equation that applies all reaction times ect.. Taken from Bosch Automotive Handbook.
But what does the 25,92 mean there?
v= velocity
tvz =...
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Do most distant objects on the Hubble diagram 'tell' as the Hubble constant has been valid for at least 60 million years?
As we all know the deeper we look into the space the further we look into the past... So if the Hubble diagram shows the most distant objects at a 20 Mpsec or ~60Mly distance from us (and as for not ...
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Estimating penetration depth of projectile in nonhomogeneous material
I need an equation for calculating the penetration depth of a projectile in a non-homogenous material. I have the values for density of each layer and the projectile, speed, and angle. Does anyone ...
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What if everything doubled linearly? [duplicate]
There is a question that goes:
Suppose you are told that the linear size of everything in the universe has been doubled overnight. Can you test it by using the fact that the speed of light is a ...
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