Classical Physics

Why the same charges forces opposite,differet ones forces each other... I know the the (-) charges mean having electron and (+) mean absence of electron but still I cannot explain where this forces come from??? Is the a reason of max. irregularity min. energy? or Is there any importants efects of photons?? or as anybody says, To explain this should I know The Theory of Quantum Electrodynamic?

why exactly do metals shine???

Beat Phenomena studies what happens when there are 2 waves, equal in amplitude, with 2 frequencies that are very close in value to each other mix in the same medium, as a result those waves will cancel each other at specific moments and add up at other moments. So for example if there are 2 sound waves with frequencies 700Hz and 701 Hz that are running at the same time, then the sound will “Disappear” once every one second!, due to beat phenomena, although both sound sources are running. while if the frequencies where 700Hz and 702Hz, then there will be a silence twice every one second. I was really amazed when I first saw it because it doesn't seem that it is goi…

Hi there Would it be possible to make a continious radiowave in a certain direction, and then find the spots where -in the line of propagation- the radiowave couldent be measured? I mean, if the radiowave have a wavelength of two meters, the wave would only cross the line of propagation three times, so along most of the line of propagation, the wave couldent be measured. Thanks for any input!

Can I say that the conjugate momentum defined by p_\phi \equiv \frac{\partial L}{\partial \dot{\phi}} is a covariant quantity?

please explain what is the exact mechanism of emission of photon by accelerated electron and the source of energy

Does anyone know whether nuclear pulse propulsion, that is, using atomic bombs to propel a starship through space, would be anything approaching being practical? I mean, I've heard it said that we could theoretically build such a space ship with current technology, but I recently saw a documentary that said that in order to get up to speed using nuclear pulse propulsion, you would have to detonate a nuclear bomb behind the ship once every 3 seconds for days at a time. That works out to hundreds of thousands of nuclear bombs, which seems ridiculously impractical to me. Where the heck would you store them? Am I overlooking something here? Or is nuclear pulse propulsion …

hey there, this is my first thread, i have registered here a long time ago, but i just read. so lets make it short, i want some help in understanding the inductive impedance unit, here "http://en.wikipedia.org/wiki/Henry_(unit)" I understood most of it but i dont get it how V.s/A is equal to s2/F and then "ohm.s" we are studing this at school, we study holt physics, partially, we skipped some chapter because ministry of education took it out of curriculum.

Why is it that a person is more readily to get shocked during the winter than during the summer? Is it because air is drier during the winter and thus the air acts as a better dielectric (closer to vaccuum conditions) and makes air a better capacitor, while during the summer the air is moist and humid and so there is greater impediance and the air is a worse capacitor.

Is space time curvature in gravity is real or it is only subjective for an observer observing from gravity free frame

When an object undergoes centripetal motion, it's centripetal velocity is always changing direction and thus it's centripetal acceleration is non-zero but a constant value. My quest is about tangential velocity and acceleration. As an object spins, it's tangential velocity is always changing due to direction and in some cases magnitude (ex. roller coaster). So this would mean that tangential acceleration is also non-zero but a constant value, correct?

I am confused about whether work is path independent or not. If one were to drop a pen from a height of 5 m or to throw a pen parabolically from 5 m, the work done would be the same-- thus indicating that work is path independent. However, when one is talking about engines and refrigerators, work is deemed to be path-dependent based on U=Q+W. Would someone please clarify and reconcile this confusion. Thanks.

We just learned in physics today that the reason light changes direction when it passes through different mediums is because it's speed changes. When it leaves the new medium and travels back into the original medium, it goes back to its normal direction and speed. How can it go back to it's original speed if it has already slowed down? Unless there is something constantly propelling light so it can regain the energy it lost. My teacher couldn't answer it, she also said because a when a light's angle changes, all that is changing is it's speed.

The Euler-Lagrange equation just guarantees that the integral is stationary. In the calculation of geodesics, how do I know that the path I found is actually the shortest distance between two points?

in the throtling process or porous plug experiment, the gas either cools (most) or is heated (hydrogen helium) when they pass from a region of high pressure to a region of low pressure. i do not understand how a gas can be heated via this expansion?...becoz we know that expansion => increase in volume => decrease in internal energy wch should => fall in temp always...but for hydrogen the temp. increses even after the decrease in its internal energy...how is this possible?

Hi i was just wondering if it was possible as far as we know today, if it is scientifically possible to create more energy than we put it. IN theory is it possible to have a machine in the future that produces more energy than we put in. So basically will we solve energy problems in the future. Thanks for any help. hope this is the right section to ask!

light speed is same allways right?light never goes faster then other light it is allways same so there is only one light that can be measured and its allways same speed and is evryhwhere its concept and realaty is constant

I am trying to understand the speed of sound formula [v=sqrt (B/p)] where v= speed of sound; B=restoring force/molecular Kinetic energy; p= molecular inertia/density. Sound travels fastest through solids than liquids and gases. Aren't solids denser than the other phases (except for water where liquid is denser than ice)? If so, then shouldn't denser materials transmit sound better? Also, what does the Restoring Force variable (B) represent on a molecular level and how should I think about it conceptually to make sense? Thanks.

How many photons do exist by units of volume of "empty space"? Of course there is no empty space if photons are going through it: there are photons. So, when I look at the sun (don't do that) my eye catches a bunch of photons coming from the star. "catch" meaning that the photons hit my eye. When I look anywhere from any direction, I can catch some photons coming from some source. If I change my eye with a telescope, turning to Alpha Centauri, I catch some photons from there. I can theoretically catch photons coming from the whole observable universe. So, at the same instant, in outer space, how many photons are coming from all sources in a single cm3? If the…

think of green and then white and lets say red and all other colours then think black and darkness darkness is missing of light ? but aint it allso black ? and black is sum of all colours?

[math]\text{Since light has energy, there is a small amount of mass equal to that energy.}[/math] [math] Given: f=1.0\times10^{15} \text{ Hz}, h=6.626\times10^{-34} J\cdot s, c=299792458 \text{ m/s} [/math] [math] Find: \text{mass of photon } m_p [/math] [math]E=hf, E=mc^2[/math] [math]\text{Equate the 2 values of E:}[/math] [math]hf=mc^2[/math] [math]m_p=\frac{hf}{c^2}[/math] [math]=\frac{\left(6.626\times10^{-34}\right)\left(1.0\times10^{15}\right)}{\left(299792458\right)^2}[/math] [math]=7.37242\times10^{-36} kg[/math] [math]\text{Compare with mass of electron }m_e=9.10939\times10^{-31} \text{ kg}[/math] [math]m_e/m_p=123,560[/math]

All, I have to teach One Dimensional, Two Dimensional, and Three Dimensional Motion to my son and have been reading quite a bit on these topics. I still have a question and would be glad if someone can help me understand or point me in the right direction. I'm worried that I might be missing something very basic. I understand that One Dimensional motion is motion along a straight line and most of the cases, for simplicity sake, it is assumed that the motion is on the X – Axis or Y – Axis or the Z – Axis. In this case, if the motion is on the X-Axis, the Y and Z values will be 0 with X being the only Dimension. But consider the case of a motion along a straight lin…

Is it possible that space is another substance? As in, earth, water, air... Space is just a substance that can be interacted with? As oppose to simply 'distance between two objects'?

I have read all the 'high-flying' posts on What is energy, exactly? thread. It has been interesting and educating. However, the question seems to remain elusive and unanswered. If you don't mind, I would like to bring this dilemma more down to earth. Years ago when feeling low on energy, I found all kinds of snake-oil peddlers pushing various energy boosters with caffeine mostly the main ingredient. Was wondering from where the energy really was coming from and found the role of mitochondria. Then Scientific American 2009 issue on page 86, on the left side, had an illustration showing how breaking the third phosphate bond of ATP releases a blob…

I had this info: q1 at origin q2 at coordinates (x2,y2,z2) q3 at coordinates (x3,y3,z3) I had to calculate the force exerted on q1. So I calculated the distances of q2 and q3 from q1. Then I calculated intensities of electric fields of q2 and q3 at origin (using calculated distances). Than I calculated resultant intensity (by adding separate intensities). Finally, I multiplied charge q1 by resultant electric field to obtain the force. So, was this correct? I'm pretty sure it was, but I'm checking.