# All Questions

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### Parallel or series connection?

Are C1, C2 and C3 connected in parallel, or C2, C3 in parallel and C1 in series with C23? Btw it appeared as a question in the basic physics Albanian A-levels yesterday. You had to find the ...
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### length contraction question

we know from eintein's theory of relativity that lets say, a ruler is travelling to a speed if light, then we can say that the ruler (from our view as observers) has shorten. but why, lets say we have ...
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### Why is the mass of even the upper limit of the possible Higgs boson is less than the top quark?

On 7 March 2012, the DØ and CDF collaborations announced that, after analyzing the full data set from the Tevatron accelerator, they found excesses in their data that might be interpreted as coming ...
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### What's the displacement between two opposite corners of a cube?

A cockroach is crawling along the walls inside a cubical room that has an edge length of 3 m. If the cockroach starts from the back lower left hand corner of the cube and finishes at the front ...
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### How much electric charge do electromagnetic waves carry?

Since electromagnetic waves have both electric and magnetic field components, which oscillate in phase perpendicular to each other and perpendicular to the direction of energy propagation. How much is ...
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### Does the global financial system violate laws of thermodynamics and energy conservation? [closed]

For the past years I am thinking about relating concepts from physics to concepts from economics. Especially since the financial crisis made obvious the instability of the financial system I ask ...
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### Leaching of radiometric material, is it possible?

I've been doing some reading about radiometric dating and I've come across an interesting find. If anybody has any additional information on this, that would be great. First my question: In regards ...
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### What did Marie Curie do for atomic theory?

There appears to be a distinct lack of agreement in the physics community on what exactly Marie Curie did for atomic theory. Many journals state that Curie was responsible for shifting scientific ...
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### How is an arbitrary operator usually denoted in quantum mechanics?

Which symbols are usually used to denote an arbitrary operator in quantum mechanics, such as O in the following example? $O \mbox{ is Hermitian} \Leftrightarrow \Im{\left< O \right>} = 0$
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### What is “International Service of Weights and Measures”?

In the Resolution 2 of the 3rd meeting of the CGPM, defining the kilogram, “the International Service of Weights and Measures” is mentioned (the French original text reads “le Service international ...
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### Why does an object when filled with water sink, but without water inside float (in a body of water)?

Why does an object sink when filled with water, even if the same object would float without water inside? For example, put an empty glass cup into water, and it floats. But if you put a plastic ...
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### Star trace in the sky

If the space of universe is expanding at fast rates..(even faster than light) Why we do not see the trace of the stars? A possible answer could be that the stars are only moving away but mantaining ...
2k views

### 4th equation of motion

Ive been given the 4 equations of motions The fourth being: $$s=ut+\frac{1}{2}at^2$$ If rearranged it forms the quadratic equation $$at^2+2ut-2s=0$$ But that means that t has 2 values. Will ...
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### Speculative experiment: A golf ball at the frontier of the universe

Consider a golf ball in the center of an empty sphere (maybe a GR vacuum, I'm not so sure). Consider this empty sphere as being the only space available to the golf ball, it is surrounded by nether. ...
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### What is the significance of the “squared” in $E =mc^2$? [duplicate]

If $c$ is just an arbitrary constant, why don't we say $E=mc$ and define the value of $c$ to be $\sqrt{299 792 458} \approx 17314$ meters per second? Or, why not use $E=mc^3$?
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### IF I touch anything at 0 volt with my hands and touch earth, will I get shock? Will charges from earth pass through me to 0 volt?

I know we don't get shock when we touch earth because we don't have anything to pass current to. What about when we touch 0 volts?
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### Why do we form cosmological theories based on old data?

Since the light we receive from distant galaxies may be between 7 and 14 billion light years away, the redshift we see indicates that the universe was expanding at that time (7 to 14 billion years ...
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### Is a vector and a unit vector dimensionless

Lets say I have a position vector $\vec r$. Is it dimensionless or does it have a dimension of length i.e $[L]$. Also does the unit vector $\hat r$ have a dimension?
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### In a dust cloud around a star, what causes bodies to form?

I couldn't find an answer to this question. Suppose a dust ring around a new star contains relatively uniform dust particles. What's the process by which they aggregate into larger bodies? I can ...
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### Does increasing the tension on a string also increase the density?

Consider a string under tension, for example, a string on a guitar. When a guitar string is plucked, it vibrates at a certain frequency. When the tension on the string is increased by twisting the ...
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### Current flow in a copper wire

How does current flow in a copper wire? If it passes through the transfer of electrons, then why does a copper wire still exist, even after losing electrons which are the fundamental particles that ...
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### How to calculate the energy required to rotate a planet?

How to calculate the energy required to rotate a planet from non-rotating state? Say the planet is Venus with equally distributed mass of $4.8676 \times 10^{24}$ kg, and desired rate of 1 rotation per ...
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### How can Maxwell's Demon erase information while a black hole can not?

It is stated, that information can't disappear even in black holes. On the other hand, it is stated, that mystic beings, like Maxwell demons, can easily erase any information if they just pay with ...
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### Why was the original definition of meter abandoned?

The meter was originally intended to represent $1$ ten-millionth($10^{-7}$) of the distance from pole to equator of the Earth along a meridian of longitude. The definition was later discarded. ...
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### Do comets spin? Why do satellites/space station not spin?

Do comets spin? Why don't satellites or space-station spin? If spin is fundamental thing, then it should be found in all (moving) objects.
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### How can there be any probability of finding the molecules clustered in half of the box,the other being empty?

Suppose,there are six molecules(indistinguishable) constantly jostling around in a box. The central configuration is when there are $3$ molecules in either halves of the box and having probability ...
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### cross over to another object that has same height with our last position, is that really possible?

I have got confused with this. Well..In that picture, lets say the height is 8m, and the car moves and going to cross over to another object that has the same height with its last position..my ...
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### If the specific heat capacity depend upon the temperature, what formula we should use instead of $Q=mc\Delta T$

Recently, I learned that specific heat capacity is not constant in different temperatures and it depends on the temperature.If I have diagram like this (consider that the red part is a quarter of ...
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### Shape of accretion disk surrounding the black hole in Interstellar (film) [duplicate]

There is a black hole, called Gargantua, featured in the recent blockbuster Interstellar. I understand why the accretion disk is bright (friction), but why does it seem to be flowing in two ...
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### What gives the higgs boson mass? [duplicate]

In light of the discovery of the Higgs boson. The Higgs Boson is a force particle which interacts with matter particles. My question is what does the Higgs Boson interact with to give itself mass.
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### Magnetic field at infinity

Does a magnetic field, generated by permanent magnets (for instance), vanishes "theoretically" (according to Maxwell's equations) at a very long (infinite) distance from the magnetizing devise? What ...
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### Schwarzschild Radius vs Gravitational Pull? Error in Model?

I am a middle-school student who for fun has designed an simulation of gravity that finds the gravitational pull & then the Schwarzschild radius of the object, I have tested the program (coded in ...
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### Why is signal bad in a tunnel?

Consider this: you are driving through a tunnel listening to your AM radio and a GPS, all of the sudden AM radio has nothing but statics and your GPS says "reconnecting - please hold". You say to ...
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