# Tagged Questions

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### Physics problems for submission [closed]

I often enjoyed solving and submitting problems in the American Mathematical Monthly and other Journals which have such problems. There is a lot of this type of thing for mathematics. But I wondered ...
681 views

### What things in our universe can be considered uncountable?

I am taking a course in mathematics that covers countability. The trick with the uncountability of the real line is that no matter how many times you divide up an interval, there would still be a real ...
30 views

### Why is the X-ray diffraction useful for studying the structure of nucleic acids?

It is well known that the double helix structure was determined by the X-ray diffraction method. But it always baffles me. DNAs are not simple crystals. They are not periodic, not at all. So how ...
82 views

### Are there any equations in physics that will always equal 1?

I am sorry to ask such a layman question but I am really interested if there are any equations in physics that will always equal one or that will always equal a number very close to one. If there are ...
35 views

### Current loop and direction ambiguity of the magnetic moment

Consider a circular loop in the XY-plane which carries a current $I$. Then it behaves as a magnetic dipole with moment $\textbf{m}=I\int d\textbf{S}$ where $\int d\textbf{S}$ is the area of the loop ...
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### What is “unity constant form” and why is it useful?

I read the following in a tutorial: The standard transfer function of a first order system is: $$G(s) = \frac{k}{s + a}$$ Arranging this into unity constant form gives: G(s) = \...
27 views

### Length of liquid in capillary tube

A long capillary tube with both ends open is filled with water and then set in a vertical position in air.What is the length of liquid column remaining in the tube ? Surface tension of water is 7.0×10−...
67 views

### A question about ultimate computation capability

If we consider the physical limit of computational capability of a system with average energy $E$, then (1) According to Margolus and Levitin, a quantum system with average energy $E$ takes time at ...
57 views

### Determine the height of a tall building with the aid of a barometer

I read a story in which an it was asked in an exam to show how it is possible to determine the height of a tall building with the aid of a barometer. This story is quite famous I guess, and the ...
35 views

### Tension in mass less string [closed]

I have encountered some problems where there is different tensions in a mass less string. How is this possible? A good example would be
77 views

### What are some physics books written in dialogue or story form, e.g., a teacher explaining to a student? [closed]

A good example would be How to Teach Quantum Physics to Your Dog by Chad Orzel.
210 views

### From where should I start in physics? [duplicate]

I'm currently attending Norwegian high school and I'm in a course where we study electricity, automation, electronics, and almost no physics, chemistry etc. So it will be at least 5-6 years before I ...
113 views

I am an undergrad physics student who has finished the first year curriculum: very basic mechanics and thermal physics; basic linear algebra; basic multivariable calculus and differential equations; ...
11k views

### Why do most formulas in physics have integer and rational exponents?

I mean, why is $F=ma$? Why not $m^{0.123}$, $a^{1.43}$ or some random non-integers or irrational? I hope you understand that my question isn't limited just to force, energy, velocity, etc.; it also ...
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### A modern version of Landau theoretical minimum? [duplicate]

Can anyone point to me any modern books that are similar to Landau's book in scope and depth, these books used to serve as the backbone that determines one’s level of scientific culture, and since ...
159 views

### The study of the physical universe [closed]

If physics is the study of the physical universe, wouldn't that mean chemistry, biology, neuroscience, zoology, history, economics, sociology, etc, wouldn't they all be subfields of physics? I believe ...
280 views

### Question about two vehicles moving toward each other, but the answer doesn't seem correct, am I missing a key concept? [closed]

The problem statement Vehicle A and Vehicle B are moving in opposite directions on the NJTP. Vehicle A is heading south toward atlantic city while vehicle B is heading north towards Hoboken. In ...
503 views

### Can a theory be proven by an experiment (or series of) that sustains it?

This is a question that I've always had but it wasn't until the recent news regarding the BICEP2 experiment that I really gave thought about it (please note that the question is general and not ...
108 views

### Does physics have some division schema which divide physical amounts into these two classes?

Does physics have some division schema which divide amounts into these two classes? : A) amounts which can be counted by natural numbers (for example many units can be counted by number of electrons,...
161 views

### Do Physics concepts build on top of other concepts?

I am taking a calculus based physics class and I am struggling. I am wondering if I do not understand some concepts, will I be unable to understand future concepts introduced in the same class? In ...
170 views

### Does physics address the topic of consciousness?

Does physics address the topic of consciousness? For instance, does physics say anything about how it might arise or what might be its qualitative properties? I'm wondering because it's interesting ...
582 views

### General physics landau [duplicate]

I've found Landau 's book for a first course in physics (not theoretical physics, its title is general physics),the book is freely and legally avaible on archive.org ,but it's from 1967,is that okey,...
1k views

### Accidental, unplanned breakthroughs in physics [closed]

There is possibly some idiom or saying like this, "If you try too hard for something, you will never get it. If you do not aim for something, it may fall on you accidentally, not as you originally ...
718 views

### Why mathematical equations can describe this world? [closed]

Since I want to understand the world, I learn physics from textbooks. But I feel there is a gap between the textbook and the world. I do not know why the equations in the textbook can control the ...
79 views

### What kind of physics topics exist? [duplicate]

The question says everything I want to know, but for more details: I enjoy studying physics but the problem is that I can't find any information with a summary of all physics topics, collected ...
251 views

### recommendation for a physics history/non-fiction book [closed]

I know that there are a lot theses being published on lives of physicists. Is there a history/non-fiction book that tracks the development of a problem chronologically? Like pieces of a puzzle. I ...
1k views

### The meaning of 'postulate' in physics? [duplicate]

What does postulate mean in physics? What is its role in physical theories? Is it possible to break physical postulates?
1k views

### How to teach myself physics needed at undergraduate electrical engineer level? [closed]

I want to learn electrical engineering on my own, specifically because I'm interested in loudspeaker design, more specifically how to design active dipole loudspeakers using DSP crossovers. I have ...
347 views

### Is There a List of Physics Formulas? [closed]

I am looking for a list of simple physics formulas - like $F=ma$. Is there any website/book that is a list of such equations?
4k views

### Why does the monitor make a cracking noise?

After switching off the monitor, there's a single crack after a while. I wonder where exactly it comes from. I know that this is normal and not an indicator of being defect. This sound is also not ...
2k views

### Is physics rigorous in the mathematical sense?

I am a student studying Mathematics with no prior knowledge of Physics whatsoever except for very simple equations. I would like to ask, due to my experience with Mathematics: Is there a set of ...
132 views

### Scales and Hooke's Law

Bob weighs $B$ kg and when he steps on a scale, the spring inside gets compressed by $c$ meters. Assuming the scale obeys Hooke's Law, if Alice weights $A$ kg, how much work is done compressing the ...
103 views

### Retarded field interaction

I was doing the following thought experiment: imagine a particle that moves at a certain velocity. Imagine also that the particle generates a field that propagates at velocity $v_f$. Well, if the ...
885 views

### Percentage of water that is void or empty space?

At the atomic level, at sea level on earth, what percentage of normal pure drinking water is void or empty space? What percentage of lead (the kind used to insulate from nuclear radiation) is void or ...
401 views

### What's the meaning of dimensionality?

I got amazed with this answer and as you can see, I had a little talk with joriki. He suggested me some examples such as the 2DEG. I'm stuck with some aspects on dimensionality, see this line: A ...
61k views

### How do you start learning physics by yourself? [closed]

I think this question has its place here because I am sure some of you are "self-taught experts" and can guide me a little through this process. Considering that : I don't have any physics scholar ...
179 views

### is there any difference between these Differential $dx^2$ and $(dx)^2$? [closed]

is there any difference between these Differential $dx^2$ and $(dx)^2$!? what is relation between them?
11k views

### Can a scientific theory ever be absolutely proven?

I personally cringe when people talk about scientific theories in the same way we talk about everyday theories. I was under the impression a scientific theory is similar to a mathematical proof; ...
150 views

### Weight on planet earth?

I was wondering : does the weight on the planet earth is equal over the years ? meaning : all the people , ground , water ,gas. does the weight stays the same over the years ?
175 views

### Why is it that when you pick up a cup from a stack of solo cups too quickly, they stick together?

Intuitively I think it makes sense but can somebody explain very clearly to a non-physics person why it is that when you pick up a cup from a stack of solo cups very quickly, the cup below it seems to ...
650 views

### interpretation of Green function

Is there a physical interpretation of the existence of poles for a Green function? In particular how can we interpret the fact that a pole is purely real or purely imaginary? It's a general question ...
10k views

### Is there any significance to 1.21 GW?

In connection with a related question on Science Fiction & Fantasy Stack Exchange page: does this number 1.21 GW make any sense? What is 1.21 GWatts? With what can you compare it? Can the ...
342 views

### Age of universe estimates

I was recently involved in a discussion on a sister site regarding how tightly coupled Physics is with the age of the Universe (and Earth). I believe that the Earth and the Universe are both billions ...
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### Are a measured object always part of the theory?

Is there a notion of measurement, which doesn't correspond to a yes/no question or with the idea of the comparison of two real world objects, which produces a real number? And does at least one of ...
1k views

### What are the frameworks of physics?

Are there physical theories in use, which don't fit into the frameworks of either Thermodynamics, Classical Mechanics (including General Relativity and the notion of classical fields) or Quantum ...
5k views

### Please recommend a good book about physics for young child (elementary school aged) [closed]

I'm looking for a book that would be appropriate for an advanced elementary school aged kids (say, 6-11 YO) describing the basics of physics (or sciences in general) in entertaining way. The ...
698 views

### What does physics study? [closed]

Wikipedia definition: Physics (from Ancient Greek: φύσις physis "nature") is a natural science that involves the study of matter[1] and its motion through spacetime, along with related concepts such ...
4k views

### Interesting topics to research in mathematical physics for undergraduates

I'm planning on getting into research in mathematical physics and was wondering about interesting topics I can get into and possibly make some progress on. I'm particularity fond of abstract algebra ...
1k views

### What is the physical definition of causality?

Maxwell's equations give a physical relationship between the electric and magnetic fields $\vec E$, $\vec B$ at the same time, which some interpret as changes in one causes changes in the other etc. I ...
2k views