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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 ...
Timothy Bomer's user avatar
1 vote
0 answers
47 views

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 ...
Lakshay Rohila's user avatar
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0 answers
40 views

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 ...
pll04's user avatar
  • 337
1 vote
2 answers
56 views

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 ...
Quantum Wonder's user avatar
1 vote
1 answer
56 views

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} ...
Rene Kail's user avatar
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-1 votes
1 answer
97 views

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 ...
SnoopyKid's user avatar
  • 364
-1 votes
1 answer
77 views

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....
Shinnaaan's user avatar
  • 1,357
0 votes
1 answer
39 views

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 ...
Evariste's user avatar
  • 101
3 votes
1 answer
143 views

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 ...
VVM's user avatar
  • 489
3 votes
2 answers
169 views

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 ...
nickodel's user avatar
  • 137
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2 answers
61 views

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 ...
How why e's user avatar
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0 answers
46 views

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)}...
Ram's user avatar
  • 1
0 votes
1 answer
102 views

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 ...
Miss Understands's user avatar
1 vote
1 answer
34 views

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 ...
Mary Cox's user avatar
4 votes
1 answer
163 views

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 ...
user267545's user avatar
0 votes
1 answer
75 views

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 ...
Aviv Cohn's user avatar
  • 605
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1 answer
54 views

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 ...
rioiong's user avatar
  • 613
3 votes
1 answer
102 views

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 ...
Pere Rosselló's user avatar
0 votes
0 answers
43 views

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 ...
BigBunny's user avatar
2 votes
4 answers
1k views

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 ...
Dhyaneshwar's user avatar
0 votes
1 answer
97 views

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 ...
Jimski's user avatar
  • 240
3 votes
1 answer
94 views

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 ...
16π Cent's user avatar
  • 101
0 votes
6 answers
160 views

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 ...
S K's user avatar
  • 45
1 vote
0 answers
45 views

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 ...
Spatium et Tempore's user avatar
5 votes
3 answers
608 views

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 ...
sleep's user avatar
  • 175
0 votes
0 answers
25 views

How does loudness decrease with distance? [duplicate]

Let's say there's a speaker in a huge open space on the Earth's surface. The speaker blares a sine wave with frequency $f$ Hz and and volume $V_0$ decibels. How does the volume (in decibels) decrease ...
chausies's user avatar
  • 1,090
-1 votes
1 answer
108 views

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 ?
Nachiket Deshpande's user avatar
0 votes
1 answer
77 views

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 ...
Quark Soup's user avatar
0 votes
0 answers
33 views

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 ...
Garth Bigelow's user avatar
0 votes
1 answer
54 views

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 ...
user371964's user avatar
0 votes
1 answer
55 views

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(...
Ernests L's user avatar
0 votes
0 answers
11 views

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 ...
Gerard's user avatar
  • 1
1 vote
1 answer
132 views

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+\...
Antoniou's user avatar
  • 495
-4 votes
1 answer
70 views

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 ...
No Name's user avatar
  • 97
0 votes
0 answers
80 views

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 ...
MikeHelland's user avatar
-2 votes
2 answers
128 views

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 ...
SleepyBag's user avatar
0 votes
1 answer
53 views

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 ...
Vojtěch Loubal's user avatar
-1 votes
2 answers
86 views

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 =...
wtknow's user avatar
  • 43
0 votes
1 answer
35 views

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 ...
Krešimir Bradvica's user avatar
-1 votes
1 answer
74 views

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 ...
curiousquail's user avatar
0 votes
1 answer
80 views

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 ...
YPS's user avatar
  • 3
0 votes
0 answers
35 views

Can a distance function be derived from a displacement function?

If I have some function $\vec{x}(t)$ that represents the displacement function for some object $x$, is it possible to derive a distance function $d(t)$ for that same object, representing the total ...
esotechnica's user avatar
2 votes
5 answers
701 views

Does work done by a non-conservative force involve distance rather than displacement?

I am a new physics teacher and struggling to piece out the nuance of work calculations for my Advanced Placement (AP) students. I feel like after a fruitful year of distinguishing between vector and ...
Mrs. Teacher's user avatar
2 votes
1 answer
269 views

How distance affect wind speed from a fan?

I noticed that when you feel the wind force from a fan close up, it feels like more force than from far away. Can someone give me an equation, where given a base wind speed $v$ in mph of the fan, and ...
Varun Rajkumar's user avatar
2 votes
1 answer
96 views

Concept of distance in cosmology

I am trying to follow some calculations in the book Cosmology by Daniel Baumann, where we have a light source and an observer, and we need to compute the area of a sphere centered at the source and so ...
Wild Feather's user avatar
1 vote
0 answers
30 views

Does work done by/against friction depend on path length or displacement? [closed]

On an equipotential surface, does the work done in moving/sliding a block of mass depend only on the initial and final position or the circuitous path (notwithstanding work done by or against friction ...
Pop Stack's user avatar
  • 111
1 vote
1 answer
93 views

Distance $r$ between galaxies inside the galaxy cluster

I am currently working on the dynamics of the galaxy cluster, so i am trying to get the distance $r$ between the galaxies inside the galaxy cluster from its centre. As a input i have RA , DEC and Z ...
Atul's user avatar
  • 11
4 votes
2 answers
199 views

Is Hubbles law due to Gravity?

Hubble's law states that Distance is proportional to Velocity. A ScienceDirect article states that Classical Hubble expansion is characterized by a proportional increase in the rate of expansion ...
user avatar
1 vote
1 answer
82 views

Calculating distance to galaxies seen through a telescope

When we see a galaxy through a telescope, say the James Webb telescope, it is said we see a galaxy as much as about 10 billion light years away. But 10 billion years ago we were much closer (because ...
S Nair's user avatar
  • 137
0 votes
1 answer
134 views

Difference between average position of electron and average separation between proton and electron [closed]

I'm not sure to understand what is the difference between those 2 terms in the hydrogen atom. The average position $\langle \hat{\bf r} \rangle$ is written $\langle \Psi^{*}|\hat {\bf r}|\Psi \rangle$,...
epselonzero's user avatar

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