Questions tagged [distance]

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Basic high school physics problem regarding the formula speed is the distance over time [closed]

A train 1 moves from a point $A$ in straight line at $38 km / h$ and after $2.5$ hours is followed by a train 2 which moves from the same point $A$ in straight line at $80$ km per hour. At which time ...
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2answers
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Is it possible to create computational substrates from a distance?

Processors are manufactured by photolithography, shining a light on a chemically prepared object. Layer by layer, an "active" object with computational capabilities results. Does/can a ...
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0answers
20 views

Discretizing kinematics of moving object

I think this is a simple question, but I'm unable to find the relationship: The relative distance between two objects at any time $t$ can be written as: $x_r(t)=x_{ro}+\int_{t_0}^{t_f}v_r(t)dt$ where: ...
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2answers
40 views

Calculating for total distance travelled vs position given $v(t)$ graph

It is currently to my understanding that the area under a $v(t)$ graph is the displacement of an object because $$\int v(t)dt = s(t).$$ However, some of the problems I have attempted recently give you ...
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3answers
47 views

Are we seen or not by an observer from a galaxy farther away than the age of our solar system?

I looked at this question. There's one answer that alludes to what I'm asking, but I don't find it satisfactory, because to me the following is still a paradox: The most distant galaxies we have ever ...
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4answers
57 views

How to define “work” on a movement of a celestial body? [closed]

A moving celestial body (such as a planet orbiting the Sun) creates infinite distance. How to relate this to Work formula ($W=F\cdot d$)? I know I must have wrong understanding about this formula when ...
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1answer
64 views

Range of a projectile as a function of launch angle [closed]

Goal: Derive an equation for range of a projectile as a function of launch angle if it started from a height > 0 and landed to height = 0 I know that the horizontal range $$ R = \frac{v_0^2 \sin2\...
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1answer
70 views

Show that the angular diameter distance has always a turning point

I have the following cosmology exercise: assume a flat Universe with a single component with an equation of state: \begin{equation} p = \omega \rho, \quad -1<\omega<1, \quad \omega = const. \...
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0answers
11 views

Angular change with camera reference point/vector change

Note: All measurements are taken/derived from 2D coordinates based on the video camera. Arm is a shorthand for angle between the hip to the armpit to the elbow. For all intents and purposes, arm can ...
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2answers
19 views

Projection of ball. find initial velocity [closed]

A cannonball is fired at an angle of 33 degree relative to the horizontal as shown in the figure bellow. It is 1930 meters in the horizontal direction from the point of launch to the point where the ...
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1answer
40 views

I don't think I understand how to calculate the distance of when objects are passing each other

You are driving a SUV with constant velocity of 22m/s. At a moment, you notice a truck 200 meters ahead of you, moving in the same direction with constant velocity 18 m/s. How far your car should ...
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1answer
29 views

Measuring Sun and Moon distances to the Earth ratio just by observing angles of elevation if upper 50 percent of Moon's surface is bright?

When the next type of calculation was possibly used for the first time? If 50% i.e. upper half of Moon were bright would the Sun-Earth to Moon-Earth distances ratio be calculated from just ...
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2answers
946 views

If two reference frames are not moving with respect to each other, do we take into account their distance apart to determine simultaneity of events?

I'm trying to clarify the definition of simultaneity and/or relative simultaneity - for now, only with respect to two different reference frames that are not moving relative to each other. There ...
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2answers
28 views

Is this question talking about displacement or distance travelled?

How far will a person travel in 15 min, driving their car down the highway at 24 m/s? when it says how far will a person travel, is it talking about distance or displacement?
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1answer
33 views

How to use this equation in real life for accurate results?

In this video, you can use the equation to solve for the distance between the ball being dropped and when it hits the ground. All you need to know is the time it takes and the gravitational ...
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1answer
25 views

Calculate if a beam of light will pass through a given point?

I'm not sure this should be in math or physics so i'm asking in both. Given a laser beam at closed reflective surface where point $(x,y)$ being the source of a laser bean which hits a reflective ...
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Parallax and redshift - has anyone used Gaia data to match objects with redshift data?

Given the recent Gaia parallax data out to large distances, has anyone used that data to match objects with observed redshift data? I have taken as much Gaia object data as I can and compared it with ...
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1answer
75 views

Hello, can anyone please help me understand and solve the problem? [closed]

ABCD is a track with a horizontal section BC of length 5 m. A 0.3 kg steel sphere is released from a point on the slope AB and it rolls towards the end D of the track. A stop watch was started shortly ...
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1answer
37 views

$\rm NaI$ detector rate dependence on distance

I used a $\rm NaI$ scintillation detector to linked to a scalar unit that counts the number of gamma rays detected from a $^{22}$Na source. I repeated the experiment for equal time intervals of 40 ...
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2answers
50 views

Does adding weight to a person affect the time taken for a person to run 20 metres?

I am doing a science experiment to see if adding weight to a person affects the time taken for a person to run 20 metres. I am needing to write some background information (1 page) and I am not too ...
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2answers
769 views

How can I calculate deceleration due to friction?

I was wondering, how can I calculate the decelerations of an object due to friction - and therefore find the maximal distance it can reach? For example, if a car suddenly brakes in the middle of a ...
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2answers
75 views

What is the analog of the equation $\frac{d^2\vec{r}(t)}{dt^2}=\frac{\vec{r}(t)}{\left|\vec{r}(t)\right|}f(\vec{r}(t))$ in Quantum Mechanics?

In Newtonian Physics the general equation for the acceleration when there is a central force is $$\frac{d^2\vec{r}(t)}{dt^2}=\frac{1}{m}\frac{\vec{r}(t)}{\left|\vec{r}(t)\right|}f(\vec{r}(t))$$ with $...
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4answers
42 views

Why is this the equivalent of distance in the work formula? [closed]

My brain seemed to stop during a review. Why is d (vt)/2 instead of vt?
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1answer
68 views

Given a fixed average speed in the speed vs. distance graph, is it the fastest to travel constantly at that speed?

Is it true that among all the ways to travel a distance $X$ with an average speed $E$ in the speed vs. distance graph, traveling with a constant speed $E$ minimizes the time it takes to complete the ...
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1answer
70 views

What is the formula for how far a sound can be heard (taking into account dissipation)?

I was trying to figure out how far can a sound of 103 dB can be heard, so I converted it in W/m$^2$ (it gave me about $0.0200$ W/m$^2$) and then I used the formula “$I=P/4\pi r^2$” to find the maximum ...
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2answers
80 views

Why distance between 2 particles is independent of frame?

I was solving question in kinematics related to minimum distance between particles there they said that distance between two particles is independent of frame the distance they both measure between ...
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0answers
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When to use which cosmological length description?

Definitions During a lecture I was introduced to several ways of expressing "length" in the context of cosmology. Explicitly, I was given the definitons ($a$: scale factor, $c$: speed of ...
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0answers
30 views

Proper distance and coordinates in Schwarzschild spacetime

Consider two points in the Schwarzschild coordinates with a line-element $ds^2=-(1-\frac{2M}{r})dt^2 + \frac{1}{1-\frac{2M}{r}}dr^2+r^2(d\theta^2 + \sin^2\theta d\varphi^2)$, where $M$ is the mass of ...
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7answers
439 views

Why does increasing voltage result in a decrease in current and not rather a decrease in power? [duplicate]

I recently read that in order to conduct electricity over vast distances via power lines they had to step up voltage which results in a decrease in current through the medium. This is reflected in the ...
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3answers
46 views

What does the first derivative of (2-norm) distance with respect to time tell us?

My basic physics' knowledge is a little rusty. My apologies in advance. I know that the first derivative of position or displacement with respect to time is the instantaneous velocity. Suppose I have ...
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1answer
30 views

Travelled distance with accelerated movement knowing terminal velocity and time [closed]

So I have a body which moves straight on a line. The body accelerates from 0 m/s to some velocity V, the acceleration is constant and I know that after T seconds it reaches its final velocity V. Is ...
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1answer
125 views

How did $4$-distance in General Relativity become displacement in Newtonian Gravity?

In general relativity the christoffel symbols 'pop' out of the metric $g^{\mu \nu} dx_\mu dx_\nu$. When $g^{\mu \nu} dx_\mu dx_\nu$ is integrated it is a measure of distance between the $2$ points. ...
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1answer
13 views

When given magnification alone,for an upright, virtual image, with convex lens, how can I find object distance [closed]

Formula involved in such calculations, similar examples, link associated with d question
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1answer
50 views

In Luminous Distance calculations, why does the power fall of by a factor of $(1+z)$?

This is a follow up to this question here about the $(1+z)$ factor in the Luminous Distance formula. As the universe expands, I understand why the energy falls as the wavelength is stretched (by a ...
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4answers
3k views

If work is a scalar measurement, why do we sometimes represent it as the product of force (a vector) and distance (scalar)?

Consider an object being pushed 3/4 of the distance around a circular track. The work done on the object would be the distance of 3/4 the track’s circumference times the force applied to the object (...
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1answer
73 views

Taking a frictionless object to a full stop given initial velocity and stopping distance [closed]

I am working on a simplistic simulation program where at some times I have to take an object to a full stop, while only knowing it's velocity and the distance in which it has to stop. Though, I want ...
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2answers
53 views

Why does calculating relative velocity with vectors yield diferrent results than with distances?

Suppose two points are situated at the origin of xy coordinate system. Two points start moving at the same time. Point $T_1$ starts moving towards north with velocity $v_1 = 2.7m/s$ while point $T_2$ ...
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1answer
25 views

About comparing distances between different frames of reference, and meter sticks

If a frame of reference $S'$ is moving with respect to a frame of reference $S$ with a velocity $v$ (along the $x$ axis of $S$), then an event $(x,t)$ in $S$ is viewed as an event $(x',t')$ in $S'$ ...
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0answers
76 views

Why is the metric used in physics a squared norm? [duplicate]

The length metrics used in physics are usually a squared norm, like the following: $$ds^2 = g_{\mu \nu} \, dx^{\mu} \, dx^{\nu}. \tag{1}$$ What other kinds of continuous metrics could we define? Why ...
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2answers
54 views

Finding the distance travelled by a fly in a room from one lower corner to the diagonally opposite one [closed]

A room has a length of 4 meters, width of 5 meters and height of 3 meters. A fly is on one of the corners and walks to the diagonally opposite one. What is the length of the shortest possible traveled ...
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3answers
129 views

What is the distance from an object at which the gravitational force is exactly zero?

It is clear that the gravitational pull diminishes with increasing distance, but I can't find the answer to whether there is a point where it becomes "exactly zero". Is there such distance? Is it ...
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3answers
514 views

What's the proper distance from the event horizon to the singularity?

How far away is the event horizon of a (Schwarzschild) black hole away from the central singularity for a radially infalling observer starting with $v=0$ somewhere outside the black hole? After ...
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2answers
196 views

Distances in general relativity

Three dimensional distance doesn't exist in general relativity because the integration of $ d \vec l $ depends on the integration path. Well, maybe there is no mininum but it must be a maximum lower ...
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1answer
35 views

Graph of distance travelled in $n$th second with time

I was asked to graph the distance travelled in $n$th second by an object with time, taking the object to be at rest initially, and accelerating with a constant acceleration of $1 \, \text{m}/\text{s}^...
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2answers
114 views

Viewing LEDs at great distance

Say I put a satellite in orbit with several LEDs on the outside: red, yellow, blue, white and green. Could I see them from the ground with consumer-grade binoculars or telescopes? If I can see them, ...
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2answers
97 views

Moon is receding from Earth approximately 4cm per year [closed]

According to the theory of relativity the universe is styled as a fabric which is depressed by a large mass and a moon, still following a straight path ever 'curves inward' toward the large mass. Now ...
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1answer
53 views

How to find distance travelled when the change in the force of gravity is not negligible? [duplicate]

Usually when on Earth we can use as an approximation: g = a = 9.18 $\frac{m}{s^2}$ s = vi + 1/2 a$t^{2}$ However, how would I determine the distance traveled in situations where the the acceleration ...
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1answer
41 views

Distance in seconds between moving vehicles

If two cars are moving in the same direction. let’s say ego car is in the front and another follower car. the speed, location in x, y coordinates of both cars are given. How to calculates the ...
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6answers
6k views

Is a light year a different distance if measured from a moving object?

The speed of light is absolute, but time is relative. So would a light-year for us on earth be a different distance from a light-year on a different uniformly moving object? Why or why not?
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1answer
130 views

Horizon problem: Angular size of the causality patches on the CMB surface

I'm having difficulties in calculating the angular size of the causally connected regions on the cosmic microwave background (CMB), as seen from Earth today. I read in several documents that this ...

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