Physics

Hello everyone I have a question I have stumbled upon.. well... playing with stuff. In my bathroom, I have some sort of cup with a chalice-like-shaped 'cover' (see attachment) The black boll is a solid metal ball at which I hold this 'cover'. The rest is, of course, hollow. Now, I've experienced something rather strange; when I tap my finger on the hollow, metal part, keeping hold of the solid ball, it produces a sound - rather logic. The strange part is, that the sound is extremely loud (well, it IS extremely loud when held less dan 2 cm from my ear) at the outer sides (outside of this 'chaliceshape') and there is absolutely no sound in this chalice shape. (So …

^Please answer it in the most basic but clearest way(Im not the best in science).Thanks alot!

I have recently started studying the photoelectric effect. I currently have very little understanding of the theory. As i understand it retarding voltage is a voltage applied to the anode and the cathode of a photovoltaic cell such that any photoelectrons emitted are decelerated just enough such that they don’t reach the anode. This is a very superficial understanding, and could be totally wrong. Can anyone help me qualitatively refine my understanding? Also, why is a retarding voltage ever used? Jack.

Optical photon is produced e.g. during deexcitation of atom, carrying energy, momentum and angular momentum difference. So how is this energy distributed in space - what is the shape and size of single photon? Looking for literature, I have found started by Geoffrey Hunter, here is one of articles: "Einstein’s Photon Concept Quantified by the Bohr Model of the Photon" https://arxiv.org/pdf/quant-ph/0506231.pdf Most importantly, he claims that such single optical photon has shape similar to elongated ellipsoid of length being wavelength λ, and diameter λ/π (?), providing reasonably looking arguments: Is it the proper answer? Are there other reasona…

Hi, Fundamental frequency is the lowest partial in signal analysis, and the harmonics of the fundamental are multiple integrals of that. But I've heard of 'subharmonics' where people are claiming that you can have integral fractions of the fundamental frequency in music. don't understand this, as I thought the fundamental was the lowest, by definition. Anyone who is clued up in Acoustics that could perhaps explain this in more depth? Is there such a thing as subharmonics and how does work in relation to the fundamental?

In a book the radius of gyration is defined as "Radius of gyration may be defined as the distance from the axis of rotation of a mass point whose mass is assumed to be equal to the mass of the whole body and whose moment of inertia is equal to the moment of inertia of the body about the axis" So can that mass point be considered as the centre of mass of the body? Acoording to me it has to be the COM. Please do correct me if i am wrong

I'm just reading about these 2 forces but I'm not really getting the difference Electromagnetic force is about attraction or repulsion between the nuclear particles of atoms, but the then what's electrostatic force? What's the link between these 2 forces and Coulomb's law: F= kQ1Q2/r^2? Please Help I'm really confused:-(

The Float Serve I am a volleyball player and also currently taking Physics in my last year of high school. I am trying to explain the odd trajectory that a volleyball follows when it is served a certain way. The Main Idea: A float serve is implemented in the game of volleyball to make it as difficult as possible for the opposing team to effectively receive and play the ball. By contacting the center of the ball with a hard hand and not following through with the swinging arm, the ball follows a very odd trajectory through the air, making it appear as if it were floating through the air (traveling side to side, up and down, and curving) WITHOUT any kind of s…

How did space come into existance?

Okay, most sources say that once you get past the event horizon, you will be ripped apart by the gravity and die. Yet, they also say that once you pass event horizon, every direction leads to the singularity. This doesn't make sense. If every direction leads to the singularity and you get pulled toward the singularity then you are getting pulled towards the singularity in every direction... Wouldn't the forces cancel out? Also, since the singularity is infinitesimally small, wouldn't it take you forever to actually get to the singularity as every part of you is approaching that which is infinite?

I have already admitted I was wrong in generalizing for massive particles. In the wave-like behavior actually the momentum p appears, not the mass. De Broglie wavelength is actually defined by their momentum p which is different for them (λ = h/p) at same velocity. But for massive particles there is a relation between the momentum p and the mass m... May be I should rethink about what I have said. The point is that in general, waves are not associated to a mass but De Broglie law precisely combines both. Definitely I must rethink about... Better to say that the wave-like behavior also omits the concept of mass although it plays a role in the determinatio…

Hello everyone, I have been reading about photometric optics and photometric units recently. I keep seeing several documents saying that the luminance of the sun is 1.6×109 cd/m2 at noon, eg Wikipedia. I tried to use the definition of luminance and some facts about the sun to see if I could calculate what the luminance should appear to be to someone on Earth, just to see if I got the same number as in Wikipedia. Well not only did I not get the same number, but my answer was off by a factor of 1030 too big! I am puzzled because I think I am using the right formulae and all the correct numbers, but still it does not match, so I am wondering where I have gone wr…

I confronted this force problem in the Physics Nelson's Textbook, and my teacher gave us a lot of other questions except this one. I told her, I wanted to do it to challenge myself. But oddly enough, I'm struggling with it. Here's the question: A traffic light hangs in the centre of the road from cables as shown in the figure. If the mass of the traffic light is 65 kg, what force must the cables exert on the light to prevent it from falling? (Hint: Since the angles that cables make with the hortionzal are the same (12 degrees), they both exert forces of the same magntiude. Any suggestions?

On a Mendocino Motor why does one side float free while the other has a tip to a wall? I know the question might sound trivial but I have worked up the idea why not use the same magnets used to levitate as a counter force on both sides of the shaft? I attached a very rough jpg of what I mean. the green magnets at the end of the shafts is what im referring to. is there some theory or law preventing this?

i've always thought it would be impossible to freeze fire. but the question stuck in my mind this morning, and i've been thinking about it all day. could you do it? fire needs heat, fuel, and oxygen to continue to burn. let's assume you have a fuel source that is small, but burns for a very long time. the fire will keep burning as long as it has air because it produces its own heat. could you freeze a fire in oxygen?

How is the dielectric strength of air affected in reality. Consider dust, humidity, temperature, and air pressure, how much lower or higher does the 3 kV/mm value go?

When a magnet is placed directly over a super conductor it will display properties of levitation. If the magnet is removed, the super conducting material will still display these properties. This is known as the flux trapping effect. My question is how do you reset the super conductor to its original state. Is it as simple as raising the temperate above the material's critical temperature? Also is there any way to avoid the flux trapping altogether and have a material that is purely diamagnetic?

I would like to define time as the "speed of one entity in relationship to the speed of another entity" i.e. It takes her 1 hour to walk around the block. (her speed in relation to the speed of the clock.) Where problems arise is when we use the word "time" in the abstract: "The time it takes for the earth to go around the sun is one year." The above statement has nothing to do with time but is the definition of a year, i.e. When the earth goes around the sun we call it a year. Yes, yes, Quarks Rule!!

all you need is a MIRROR. It works on the principle that, when you look at yourself in a mirror, you arent seeing YOU, per se, but the BACK IN TIME you. How? When you look at a mirror, the light rays start off at your eyeball, bounce on the mirror, get reflected back off into your eye, thus creating the mirrorical picture you see. Now. it takes TIME for those light rays to do all that stuff, going off your eyes, travelling headfirst into the glass of the mirror with a bang, then painfully lugging the picture off the mirrors surface into your eye again. all this takes time, init? light travels at 3 million miles per second, which means it takes 0.0008763 seco…

This is a quote of somone on another forums explaning to the other forum members what I ment when I was trying to discribe an anomile I encountered while playing with magnets The orriganal post is here http://www.steorn.net/forum/comments.php?DiscussionID=17702&page=1#Comment_260721 Please can I have some feedback

Hello everyone, Why does the velocity of flow decreases as the cross-sectional area of a tube increases. If a tube was constricted for sometime, its flow rate would be low due to resistance, now if you dilate the tube, the flow rate should increase. Am I confusing flow rate with velocity of flow. When they say velocity of flow do they mean, that when you dilate the tube more particles travel slower, but since there are more particles flow rate would be high. Thanks

http://en.wikipedia.org/wiki/Magnetic_charge - "monopole detection is an open problem in experimental physics" - "magnetic monopole particle has never been conclusively observed" - "has never been evidence for the existence of magnetic monopoles" How come magnetic monopoles supposedly do not exist, and why would it be hard to find evidence and conclusively observe magnetic monopole fields if all we need is a battery, wire, permanent magnet and know about Ampere's law? http://en.wikipedia.org/wiki/Ampere%27s_law So, obviously magnetic field of a moving charge has only one pole, right? Magnetic dipoles look like this: http://…

That have zero mass in what sense? Your use of the term "mass" is contrary. When you choose to say that light has zero mass then you have chosen to use the term "mass" to mean "proper mass". The proper mass of a particle does not change its value with c. Therefore the assertion that Einstein showed that a massive particle can't travel at c because its mass would become infinite is then am invalid statement.

Is it possible the Lorentz force regulates a the ground state in hydrogen.. If no, why not? Using the Bohr magneton it seems some atoms actually have pretty strong magnetic fields, which could have enough force to be a "ground state" energy source/regulator.

How can you calculate the thermionic work function of hydrogen? Thanks in advance.