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1
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2answers
87 views

Dragon Ball Z: Hyperbolic Time Chamber *(also increased gravity training) [closed]

Firstly, I am sorry if this seems like a joke. It is not. I have always loved the Dragon Ball series, so this question has been on my mind for a while. Can ...
2
votes
1answer
41 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 ...
0
votes
3answers
102 views

Do negative numbers have any physical meaning?

So, mindlessly wandering off into space, thinking about quantum and how cool physics is, I came to a realization that... well.. negative numbers to me make 0 sense. You have either something, or not ...
1
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0answers
44 views

Is entropy a dynamical quantity [closed]

I am confused whether Entropy is a dynamical quantity or not. Gibbs entropy, and quantum mechanical Von Neumann entropy.
2
votes
3answers
90 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 ...
0
votes
1answer
107 views

Why isn't steam/cloud blue like liquid and solid water?

Most of us here are aware as I think that pure water has a natural quest to absorb visible red colour wavelength slightly due do which liquid water and sometimes even ice appears to have a blue colour ...
0
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2answers
292 views

Difference between pressure and stress tensor

What is the difference between hydrostatic pressure and stress tensor?
4
votes
2answers
86 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 ...
1
vote
0answers
212 views

Physics for Civil Engineering (Earthquakes, Materials Science for structures) or Fluid Mechanics? [closed]

I am currently a first year Ph.D. student in Applied Math. As an undergrad, I did not have the opportunity to take a calculus based physics course and the one I took was a general physics course where ...
-9
votes
1answer
134 views

General Physics II Practice Question [closed]

I have a test in a few hours, and my professor gave us a practice test, and I'm stuck. Could you give me a hint as to how to approach this problem, equations I could use. It's an algebra based class ...
-4
votes
1answer
68 views

Water level rise due to body in water

I recently came across a comment that when we push a rubber ball into water filled in a bucket, the water level rises because of the force applied by our hand (i.e. the more force we apply, the more ...
-2
votes
1answer
91 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 ...
1
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1answer
124 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 ...
0
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2answers
295 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 ...
14
votes
3answers
629 views

Accidental, unplanned breakthroughs in physics [closed]

There is possibly some idioms 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 ...
2
votes
5answers
424 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 ...
0
votes
0answers
76 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 ...
3
votes
1answer
640 views

Do quantum computers manufactured by D-Wave Systems, Inc. work? [duplicate]

D-wave claims to have built 128 qbit quantum computers which are commercially available? What I don't understand is that have they really been able to do this given that the scientific community is ...
1
vote
1answer
130 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 ...
1
vote
1answer
514 views

Power radiated by the sun at different locations

I am wondering can someone help to solve second part which extends first part; The power radiated by the sun is ${3.9*10^{26}}_{watt}$. The earth orbits the sun in a nearly circular orbit of radius ...
2
votes
2answers
428 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?
0
votes
2answers
657 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 ...
1
vote
0answers
312 views

What are the biggest unanswered questions in physics today? [closed]

Are there fundamental big questions in physics that most scientists encounter no matter what they're working on, or are most questions details of smaller subtopics? What are the great unknowns of our ...
-6
votes
1answer
266 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?
3
votes
1answer
1k 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 ...
11
votes
7answers
1k 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 ...
1
vote
0answers
120 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 ...
1
vote
1answer
100 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 ...
-2
votes
1answer
402 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 ...
1
vote
3answers
1k views

when an object moves downward, is its height negative?

the question is: A ball is thrown directly downward with an initial speed of 8.00m/s from a height of 30.0m. After what time interval does it strike the ground. so i went through the problem and ...
2
votes
2answers
114 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 ...
4
votes
4answers
1k views

Why the breath sometimes warm and sometimes cold? (2 different explanations!)

If you blow air against your hand with your mouth open, you feel warm breath. If you do with with your lips closed except for a small opening, you feel cold breath. One explanation from here says ...
12
votes
11answers
19k views

How do you start self-learning physics [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 ...
0
votes
1answer
160 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?
6
votes
6answers
4k 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; ...
0
votes
2answers
129 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 ?
1
vote
1answer
86 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 ...
4
votes
1answer
314 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 ...
3
votes
1answer
9k 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 ...
1
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5answers
298 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 ...
0
votes
1answer
72 views

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 ...
4
votes
7answers
741 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 ...
4
votes
3answers
2k 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 ...
2
votes
3answers
416 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 ...
6
votes
3answers
2k 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 ...
6
votes
4answers
673 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 ...
4
votes
1answer
1k views

Cooking pasta: why does adding a lid lead to overflow?

When cooking pasta, some organic foam usually forms on the surface of the boiling water and the situation can be kept under control by adjusting the heat (and/or adding some oil). Covering the pot ...
25
votes
4answers
8k views

Why can't energy be created or destroyed?

My physics instructor told the class, when lecturing about energy, that it can't be created or destroyed. Why is that? Is there a theory or scientific evidence that proves his statement true or ...
8
votes
4answers
301 views

What fundamental principles or theories are required by modern physics?

We have been taught that speed of light is insurmountable but as we know an experiment recently tried to show otherwise. If the experiment did turn out to be correct and confirmed by others, would ...
1
vote
0answers
89 views

Practical personal aircraft today? [closed]

Is it possible to build, today, a personal aircraft that not use an impracticable amount of fuel for everyday use? What are the physical concepts that could be used to build it?