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-5
votes
1answer
47 views

Calculate Time from Distance, Initial Velocity and Final Velocity [closed]

How can I calculate the time given the traveled distance, initial velocity and final velocity? I've found some algorithms that include acceleration, but in this case there is constant acceleration. ...
0
votes
0answers
28 views

Scalar invariance and dimensions

I recently read an interesting article on scale in variance http://www.wired.com/2014/08/multiverse/ It discussed how modern physics is suggesting that scalar units really may not apply above the ...
0
votes
0answers
31 views

Does this calculation give displacement or distance?

So we have velocity as a function of time given $\overrightarrow{v}(t)=(1-2bt)k\overrightarrow{r_0}$ where $b,k$ are positive constants and $\overrightarrow{r_0}$ is a unit vector. It is found that if ...
1
vote
2answers
20 views

size at a distance

Can someone help me please. If I held up my thumb at full arms length into the sky. My thumb is the width of an object I am looking at, at 2000 meters away. How big is the object in the sky?
1
vote
1answer
57 views

Projectile motion with air friction force/resistance [closed]

We have to find the x (the distance, if you didn't know that then I'm not sure if you should be doing this problem) that the projectile travel during the time in the air until the time it hits the ...
5
votes
1answer
54 views

How to define the distance between two points in a conformal transformed space?

Consider a particular conformal transformation $x^\mu\rightarrow x'^\mu$, and the metric of a flat space transforms in the following way, $$\eta_{\mu\nu}\rightarrow g'_{\mu\nu}=\Lambda^2(x)\eta_{\mu\...
3
votes
1answer
90 views

How can we define the distance for a pair quantum states in phase space?

In condensed matter physics, we know that two degenerate ferromagnetic ground states $|\uparrow\uparrow ...\uparrow \rangle$ and $|\downarrow\downarrow...\downarrow\rangle$ are far from each other in ...
1
vote
1answer
58 views

What type of instrument can I use to determine my current distance from the center point of Earth?

Immediately, I think of a scale, but is there better way? I can only imagine weighing an object of known mass with an extremely precise scale. I am asking because I would like to be able to address ...
0
votes
1answer
15 views

Relyance of plate distance on the capacitor equation

I am studying capacitors and i cannot seem to understand why the increase/ decrease in voltage and distance between the plates would affect the capacitor's abillity to store charge. Can anyone help??
6
votes
0answers
62 views

A 'distance' measure that involves 3 quantum states

The following question was asked by my friend Elie Wolfe. Given two quantum (or even classical) states $\rho, \sigma$, there are various measures that say how 'far' these two quantum states are, such ...
0
votes
0answers
26 views

Why is light redshifted?

I heard that very distant stars can be seen as red. Why does light become more 'redder' when travelling long distances? My guess would be it loses some sort of energy, but can't seem to figure it out ...
0
votes
1answer
55 views

When two like charges are placed at a large distance from each other, do they attract each other? [closed]

So my friend and I were arguing about this. He insists that if two like charges are placed at a large distance from each other, they attract each other. I find this nonsense. This clearly violates ...
0
votes
1answer
46 views

What determines the color of photon that is emitted from an exited atom?

I understand the principle of how light is emitted from an atom. What I don't know is why neon atom is red and copper is green when exited? Is is the distance between the electron to protons or the ...
-1
votes
1answer
25 views

Why is the first part of equation i.e $v_0(t_f-t_0)$ not considered while plugging real life problem to it? [closed]

Why is the speed*time stuff is not present while we look for the distance? I got it from this (physics for dummies)
-1
votes
2answers
55 views

How can we find out the distance to a galaxy using redshift?

As redshift occurs due to Doppler effect and universe expansion, how do we know what part of the shift is responsible for which, in order to determine the distance to the object emitting the waves? Is ...
0
votes
2answers
44 views

Distances between stars and their sizes

At the begining I wish to apologise for naive question, but one thing puzzles me. Let's say we observe two stars that have average brightness. One can easily see that they are not points, but those ...
0
votes
0answers
18 views

What is the Reach distance of a laser beam? [duplicate]

How far can an uninterrupted beam of laser travel? And on what factors does it depend on?
0
votes
0answers
33 views

How to derive velocity, distance from a changing acceleration?

I'm making a electronic device that is out of the scope of this site, but essentially it gives me acceleration readings every X microseconds. Given these samples of acceleration, how can I find out ...
1
vote
2answers
98 views

How Far Does Gravity Extend? [duplicate]

How far does gravity's influence extend? I've recently (re-)seen 'The Universe' season 1 where it's said that 'take these two dice, place them perfectly still in empty space 1 inch apart and within ...
4
votes
4answers
193 views

Distance in General relativity

I read a few lines about general relativity and one of the first equations is the one defining the eigentime of a time - like curve. But observers should also be able to measure length, right? So is ...
1
vote
1answer
57 views

How does one calculate how big something has to be, to be seen at a given distance? [closed]

Ignoring curvature of the Earth. How do I calculate the size an object would need to be in order to appear to be approx 1cm tall at a given distance?
0
votes
1answer
56 views

What is the resistance force of a ramp?

I know that the effort force is what you exert on the object, the effort distance is the length you walk on the ramp, and the resistance distance is the height that I traveled (or height of the ramp), ...
0
votes
2answers
74 views

Perspective Redux (why objects seem smaller as the distance increases) [duplicate]

Last time I brought this up, the best answer featured an image that looked something like this: The argument here is that as the distance increases between the eye and the object, the angle gets ...
1
vote
1answer
54 views

Is there an underlying reason why some forces are inversely proportional to the square of the distance? [duplicate]

This is the first time I'm studying those subjects (I'm still in high school) and my teacher couldn't give me an answer. I'm referring specially to Newton's law of gravitation and Coulomb's law of ...
16
votes
9answers
4k views

Why do objects appear smaller when viewed from a distance? [duplicate]

Yes, I know all about perspective (I'm an artist). I even have some basic knowledge of descriptive geometry. I know how it works. My question is more about why it works. I have a sneaking suspicion ...
1
vote
1answer
27 views

Distance formula using initial velocity and acceleration

we know $S=ut+1/2at^2$. Now lets say my initial velocity $u=10m/s$ and acceleration be $a=5m/s^2$. In first second distance traveled $S^{_t=1}=10m$ as my speed is $10m/s$ and time is $1s$. In next ...
1
vote
0answers
24 views

The angular diameter distance for a radiation dominated universe

I'm attempting to work out the angular diameter distance for a radiation dominated universe, with $k=0$ and $\Lambda=0$. I have gotten myself to this point: $$ D_{A}=\frac{1}{H_{0}(1+z)}\int^{z}_{0}...
3
votes
2answers
79 views

If displacement is 0, why isn't the work performed on an object 0?

Work is force x distance/displacement. The exact definition is something I'm a little confused about since my professor said it could either be distance or displacement. So going with that, if the ...
1
vote
1answer
106 views

Distance from Earth where gravity becomes negligible

This is a basic little problem I thought up when trying to remember some physics, and I wanted to see if it's at all correct: trying to figure out the distance from earth where gravity becomes ...
1
vote
0answers
44 views

Measuring distance in a spaceship moving with 0.5c [closed]

If there are a spaceship moving at a speed of 0.5c that sent a photon when an asteroid was exactly $3\times 10^8$ m away, will the distance between the spaceship and the asteroid when the photon hits ...
0
votes
1answer
35 views

How to calculate the diameter of a moving circle from afar while lacking and knowing some information?

Let's say there is a solid wood wheel with two tires attached at the bottom travelling on a level road towards me while facing me width-wise (as in, the side of it from which you can see its diameter)....
-2
votes
1answer
51 views

Can motion be characterized without time as independent variable? [closed]

I was just thinking about speed = distance/time which relatively describes how fast something is moving wrt some still object. So if by some wishful thinking or some coordinate system I remove the ...
1
vote
4answers
88 views

Distance can be zero

Can a distance between two particles can be exactly zero? Example: If I have two opposite charged particles having uniform charge. They will attract each other and the distance between them will ...
1
vote
0answers
52 views

Can a photon be captured in a grid space representation at a fractional Planck position?

Consider a photon, positioned in space in a finite portion of a grid. Any point of the grid is vertically or horizontally aligned, each distanced by a Planck unit. $l_P = 1.616 199(97) × 10−35 m$ ...
1
vote
2answers
121 views

How far do we need to be removed from the earth to show the curvature with a viewing angle between 42 and 48 degrees? [duplicate]

I have seen already a couple of answers but none of them give an exact number of what should be the minimum height where we would be able to record the curvature of the earth All I could find is ...
0
votes
1answer
99 views

Why is the potential energy minimal when the repulsion and attraction force between molecules is 0?

According to this potentialcurve and the other curve(?) the potential energy is minimal when the intermolecular forces equal zero. Why? How should I interprete negative potential energy in this ...
0
votes
0answers
11 views

Blocking Window Distance Estimation in sCMOS Sensor setup

I am trying to establish an appropriate distance between a spectrograph output window and a CMOS sensor. The spectrograph creates a focussed image on the CMOS sensor, but I need to block out some of ...
1
vote
1answer
39 views

When measuring distance how do we know when supernova comes from binary star and not single one?

The way I understand distance is measured for far out objects is by binary star supernova, since at the point of explosion there's is always same amount of energy released. But then supernova can ...
0
votes
1answer
40 views

Calculating position of a particle at time $t$ in a gravitational field

I'm working on a piece of code that is supposed to visualize a particle bouncing up and down from the ground (somehow magically we can give it velocity upwards when it is on the ground). I figured ...
1
vote
1answer
38 views

Distance between two charged particles [closed]

Is there a way I can find a function $r(t)$ that gives me the distance that separates a charge $q$ and another charge $Q$ knowing the initial velocity of both $v_{01}$ and $v_{02}$ and the initial ...
1
vote
1answer
227 views

Is there a minimum distance? [duplicate]

I would imagine there is no limit to how small space can get. Is this correct? I am aware of planck's constant, but cannot objects be closer than Planck's constant is short? Perhaps this question is ...
1
vote
1answer
60 views

Difference between Distance and Space

So I take particle A and place it in space, then I place particle B 1,000,000 light years away from particle A. I strike a line between the two, and measure that line as having a length of 1,000,000 ...
2
votes
3answers
1k views

If UV radiation 1 cm away from the halogen bulb is equal to Sun's radiation, what is the level of radiation 1 meter away?

Halogen light bulbs emit some amount of UV radiation, and some sources consider them dangerous. Here it is written, that UV radiation (of certain types) from a particular halogen bulb was equal to the ...
-1
votes
1answer
33 views

Why is $\theta$$ = $$\theta$$_{2}$ and not Phi in this Magnetic Field due to Current in Loop Equation [closed]

I'm wondering how we know that $\theta$ = $\theta$$_{2}$ (essential to solving the problem) and that it is not equal to, for example, ϕ?
1
vote
2answers
65 views

Can meters measure a distance in higher dimensions?

Consider meters as a unit of measurement. Meters can, of course, be used to express distance across a two-dimensional plane. E.g. The distance from your chair to the door is 2 meters. Meters can also ...
0
votes
1answer
36 views

Formula for speed of rigidly connected objects with one “turning off” of the line?

In the diagram below I have two objects traveling up the diagram on the black track at some speed s, separated by distance D connected by a breakable rigid rod. Further along the straight-line track, ...
0
votes
2answers
87 views

Derivation of a kinematical equation [duplicate]

My question is, we can calculate distance of free falling objects with the equation of $d = \frac{1}{2}gt^2$ where $d$ is distance in meter, $t$ is time in seconds, but I wonder how we achieved this ...
1
vote
1answer
330 views

Is displacement in circular motion a chord or an arc?

When taking the displacement between two points along a circular path to calculate its velocity, do you take the length of a chord connecting the two points or do you take the length of the arc ...
0
votes
2answers
91 views

Gravity Vs Distance [closed]

What is the relationship between the magnitude of Earth's gravity and the distance away from the Earth's surface? Or at what rate does gravity decrease as one moves away from Earth?
0
votes
1answer
185 views

If there is a boson that carries mass, why not space, or time? [closed]

If the Higgs Boson carries mass, why doesn't there exist more bosons that carry other fundamental properties such as volume/distance (space), time, or even spacetime? Also if bosons carry force, but ...