# Questions tagged [distance]

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### How can I find the distance someone moves with the effects of deacceleration due to friction when im only given the change in velcoity from time? [closed]

I was given a problem to work on that said to calculate how far someone moves as they slide across the floor and with the effects of friction acting on them. However, the only variables they gave me ...
84 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 ...
56 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 ...
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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 ...
1 vote
41 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 ...
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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 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 ...
42 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 ?
63 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 ...
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 ...
47 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 ...
35 views

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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 ...
46 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 ...
113 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 ...
47 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 ...
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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 =...
30 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 ...
1 vote
79 views

### Time dilation under constant acceleration

If I am given: the distance of two points the (constant) force being enacted on the object moving between those two points how can I figure out: the time it would take the object to reach the other ...
56 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 ...
74 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 ...
31 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 ...
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### How do you find the time an object stops per hour after getting the maximum speed, and average speed that accounts for stop time?

A bus travels at 54.0 km/h while moving but after accounting for stopping time, to let passengers on and off the coach, it averages a speed of 45.0 km/h. How many minutes does the bus stop for each ...
1 vote
381 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 ...
162 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 ...
87 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 ...
1 vote
27 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 ...
1 vote
71 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 ...
193 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 ... 1 vote
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### 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 ...
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### 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 $\langle \Psi^{*}|\hat {\bf r}|\Psi \rangle$,...
1 vote
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### Is clause "distance doesn't depend on frame of reference" an axiom in Newtonian Mechanics?

Consider 2 object is 1 and 2, at time t1: 1 has position is C and 2 has position is A. In frame of reference 1 (1 is stand still), from time t1 to time t2, 2 moves from A to B In frame of reference 2 ...
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### How can the distance to the Sun from the Earth be determined without relying on any prior baseline measurements?

I am asking if there is a way that a man could determine the distance from the earth to the sun without already having a baseline distance or dimension measurement to begin with, and without having ...
72 views

### Energy conservation, photon, distance

From Weinberg 1972 Gravitation and Cosmology Principles, when discussing the luminosity distance, he talked about due to light wavelength being stretched as well as time interval stretched, in the &...
35 views

### The "overlap function" of a $Z_2$ gauge theory

Consider a $Z_2$ gauge theory on a square lattice (Ising spins on edges) with classical degrees of freedom, i.e. \begin{equation} E = -\sum_{\square} \sigma_i\sigma_j\sigma_k\sigma_l \end{equation} ...
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### Proper distance in terms of the deceleration parameter

So, in an effort to connect theory to measurable quantities, in the Ryden cosmology textbook the scale factor is Taylor expanded as $$a(t) \approx 1 + H_o (t-t_o) - \frac{1}{2}q_o H^2_o (t-t_o)^2$$ ...