Physics

How to Derive an Expression for Electric ptential energy for System of n' charges?

I'm reading The Night's Dawn Trilogy and Haimlton mentions this pretty often. The rest of the story is full of proper scientific concepts, but the only references I found about vacuum ablation say it's nonsense. Certainly, the idea that materials would "boil away" in empty space doesn't sound very convincing. Is vacuum ablation real? At what pace would a spaceshuttle hull ablate? And what is it that really causes the ablation? Radiation? The cosmic microwave background?

Giving this another honest shot. It's said that long ago, we proved that a source of light traveling either toward or away from measuring equipment will still emit light that will be measured at C. The only ways I would know to measure the speed of light would involve bouncing that light off of an array of mirrors. My question is: Does anyone know of a an experiment to measure the speed of light from a source moving relative to the measuring equipment that used a method that did not involve reflecting that light through a mirror array? Can anyone describe how it would be measured without a mirror array?

Would it, in pure theory,be possible to send a longitudinal wave through a material at such a rate that the waves have a frequency so high that it is comparable to the frequency of gamma or cosmic waves? And what would the result be on that material? I would be concerned about the vibration ensuing would literally tear the material apart in manner similar to ultrasound shattering glass or pulversing kidney stones. Or would the energy transfer and vibrations cause the material to simply heat up?

Hello everyone I discovered something amazing: physics in daily life; more specific: electromagnetism. So I took the plug of my pc speakers (10V, 0.5A, 50/60Hz), put the volume on the maximum, and experienced first of all that the speakers emitted a sound when the plug was touching my hand. If I took my hand very close to the keyboard of my laptop, another sound was emitted. If I put my hand on my microscope (plugged in, 5V, 1A), another sound. My desk lamp of 11W, 230V caused the loudest sound. When I touch the lamp, but not the plug, another, very weak sound, gets louder when I close in to the plug with my other hand. This is rather logic, to me: B is propor…

I have been taught that chlorophyll flouresces and emits heat when exposed to certain waveleghts of light. my question is when light strikes the electrons in a flourescent material, do the electrons break free from the atom/molecule they were originally bound to? is this what happens when a molecule is said to be excited?

We know two things: 1. CO2 is heavier, thus more CO2 is in the basement 2. flame is lighter, thus flame points to forward. So can you derive that 3. more CO2 at the rear? 4. What about Oxygen?

Are motion detectors set at 60 seconds or 1 minute?? This information comes from From: "Properties of Periodic Motion." From the Phsics Classroom: http://www.physicsclassroom.com/class/waves/Lesson-0/Properties-of-Periodic-Motion It talks about a mass on a spring bouncing up and down a fixed position, and says that a detector is used to measure the periodic motion of this mass on a spring. What confuses me however are the figures. It states that a detector measures this at 0.60 seconds in the vertical Y direction, it also states this: The small deviation from 2.3 s in the third cycle can be accounted for by the lack of precision in the rea…

Hello friends, I would like to introduce a concept that has been brought to my attention through my understanding of Magnetic Fields at the conceptual level. Firstly to introduce myself, I am a Computer Science student with passions in just about all subjects including but not limited to Astronomy and Physics. My experience in application is limited but my understanding of concepts is stable. Intro As we know Solar Winds particularly effect our atmosphere through spikes that affect electronic equipment through these surges of disturbance in the magnetic field of our home, Earth. This effect poses an interesting interaction between the Magnetic Fields on our planet …

Serious question. Why couldn't the Large Haldron Collider have been put on a microchip? Crazy thought, maybe. But a serious question.

In a science fiction show they were telling that due to space dust earth's mass increases with millions of ton per day , is it real ?

Hello In my papers in preparation for the med school approval exam, there's an exercise I don't really understand: the professor who solved the exercise, failed to explain why the magnetic induction at the top of A is, as it is in the bottom, pointed in the plane of the paper (cross), same for B, and why it is pointed out of the paper under points C and D. (see drawing) Asked is the point in which the magnetic induction is zero. I do understand that both conductors give the same magnitude of induction in C (which is the answer) but I don't get why the directions are opposed. Could someone please clarify this to me? Thanks.

Hello Another question of my med school approval exam: (Really don't know how to begin this one) A fish swims 80 cm below surface. The breaking index of water is 1.33. The depth at which a person who looks perpendicular on to the water, right above the fish, sees this fish is A. 33 cm B. 60 cm C. 75 cm D. 107 cm --- So I began with Snell's law: [math]n_1\cdot\sin{\theta_1}=n_2\cdot\sin{\theta_2}[/math] [math]\Leftrightarrow -1=1.33\cdot\sin{\theta_2}[/math] [math]\Leftrightarrow\sin{\theta_2}\approx -\frac{3}{4}[/math] So [math]\theta_2 \approx 50^{\circ}[/math] But I don't know if I am something with this? Could someone help me on this …

Hi, I watched a BBC documentary recently about the string theory, super-gravity theory, and the big bang theory. The conclusion was, in short, that the generally accepted theory at present is there are 11 dimensions (ten spacial that make up an interconnected membrane of matter, and the other time) in our universe and the big bang was the result of the rippling membranes of two other universes colliding. The documentary was quite old. I'm just wondering, is this still the generally accepted theory? Have there been any developments in the theory since that documentary was made? The name theory was M-Theory and the name of one of the major contributors to the thoery…

Hello A question in preparation of my med school approval exam: "A small ball with a mass of 25 g falls with a constant velocity of 0.1 ms-1 in oil. The frictional work, done by the oil if the ball has dropped 40 cm into the oil, is: A. 0.100 J B. 0.000125 J C. -0.100 J D. -0.000125 J --- Here's how I'd like to solve this: According to Newton's second law: [math]\sum{\overrightarrow{F}}=m\cdot \overrightarrow{a}[/math] Since the ball travels with a constant velocity, [math]a[/math] and thus [math]\sum{\overrightarrow{F}}[/math] must be 0. As far as I'm aware of, there're only 2 forces influencing the ball: gravitational force [math]\overright…

This is more a question then anything but is it true that an atom is mostly full of nothing and the electrons whizzing round are like a few flies inside a chapel?

why electron microscope uses electrons when the de Broglie waves 0.01 nm energy of the electron = 7000 Electronvolt if the electron, replace the uranium atom, at a wavelength of 10 nm, the power of the atom will amount to 0.01 Electronvolt 0.01 Electronvolt is not dangerous for the studied material why is it not used?

Hi, Do EMP devices exist that can disable/power off all electronic devices within a given radius? Eg. Such as the one contrived in Prison Break season 3 episode 5. I was once told by a Russian friend of mine that when he was in school, his friend had made such a device to power off people's mobile phones with a range of about 5m. How do they work? Are they used in police/military operations? Thanks, pyroglycerine

Why is energy equal to mass times the speed of light squared? It doesn't make sense to me. Why squared? Why the speed of light?

It is stated that the speed of light has no mass and does not exist in this dimension. IE Statically known to exist in the known regions of time but not space.. Also the consideration of particle waves adds more speculation to the OP's question. If a person were standing in-front of a mirror and light rays were present, how can " information" from the light beams travel into the retina to the brain and project a virtual image for the observer upside down??--> again photons carry no information, are mass-less and do not exist in this dimension... This would also mean that depending on the person seeing themselves in the mirror that "distance" is an issue, I…

As a cosmic observation the unique characteristics of galaxies appear to have a correlation to the kinetic energy exhibited by the central black hole. The direction of rotation of the black hole appears to be ascertainable by the shape of the galaxy, particularly the position of the outer arms of stars. Also, the planar nature of galaxies appears to result from the rotational velocity intrinsic to the black hole. - Side question, is it likely that there were bodies outside of the galactic plane affected by the rotational velocity of the black hole that would have collapsed into the black hole thereby increasing it's mass initially? Does the rotation of a black…

have: proton mass 1.67*10-27 kg and speed 10 000 km/c = de Broglie wave - A electron mass 9.1*10-31 kg and speed 10 000 km/c= de Broglie wave - B and atom of hydrogen consisting of proton and electron. mass atom of hydrogen 1.67*10-27 kg + 9.1*10-31 kg , speed 10 000 km/c question what will be de Broglie wave atom of hydrogen? alleged options: 1: the electron of the hydrogen atom = de Broglie wave - A the proton of the hydrogen atom = de Broglie wave - B this seems logical 2: de Broglie wave atom of hydrogen= С ( С<B and C<<A ) this option seems not logical,because the electron in the atom has a mass of free electron and the el…

Hello to you all, my name is Leonardo and i'm 17, i was studying for the tomorrow's phisic test when i wondered what would happen if antimatter and matter "walk up".. Would there be gravity or it could be called antygravity? I thought that if the eletric force has a positive part and a negative part, maybe matter and antimatter could act as the same! Do you know something about it? Now i feel a little stupid, i'm just a guy who can't neither speak well english.. Ahah ok that's all, bye!

Would any one please explain me the working and use of capacitor (commonly called condenser) in a fan . Please don't tell the working and use of a simple capacitor.

Alright guys if the locomotives have their front surface completely straight then the force acting over it is maximum in some cases might not cause locomotion move but if it has an angle of 45' the force reduces to half but if it reduces to 30' or something less still it remains same . So does it mean that the force acts maxima 45' only.