you answer this question but it is not enough please take me a book online or take me more reasons about this.I think electric field or electromagnetic have effect about this.please explain more or take me ID from physics teacher.thank you very much for answers.
200071
The static coeffiecent is larger simply because it is harder to move an object on a surface from rest than to keep moving the same object on a surface. That is all the coefficent is is an observed value for a certain object on a specific surface.
32055
None of them, coz a magnetic field does not affect static charges.\n\nUnless that was the answer you were looking for, I get a feeling something is amiss in the question.
391144
It's because p waves are faster than s waves, so the difference is related to how far away the source is.  The bigger the difference, the farther away.
534783
The earths magnetic field is static, but an Alternating Current source will fluctuate, reversing its  North-south polarity 60 times a second.\n\nThe affects of fluctuating magnetic fields are very different from the effects of a fixed field.\n\n"A strong changing magnetic field can induce electrical currents in conductive tissue, such as the brain. Since the magnetic field will penetrate tissue, it can be generated outside of the head to induce currents within, hence Transcranial magnetic stimulation. These currents will depolarize neurons in a selected part of the brain, leading to changes in the patterns of neural activation."\n\nSee the link below for more details:
222262
Sounds like a Math/Science type question to me. Why are you posting it here?\n\nBesides, I have the the slightest idea.
453814
The wavelength is shorter but the speed is the same, so the oscillations in the field are at a higher frequency, and that means it takes more energy to create them and they provide more energy when they are absorbed. Something like that.
9476
The energy isn't destroyed, but it is reorganized into different forms.  Think of it this way: Imagine you have a bunch of fridge magnets with words on them, and you arrange them into a brilliant poem.  When you come back later, someone else has rearranged the magnets.  All of the magnets have been "conserved"-- they're still there, and they're just as magnetty as ever-- but the particular shape that they were in when they were your brilliant poem is unrecoverable.  Sorry. <3
2621
here's a site with pics that might give you some ideas:\n\n\nhttp://www.physics.usyd.edu.au/competition/comp1998/comp98.html
577613
Well, take a look at this:\n\nhttp://www.answersingenesis.org/docs/2.asp
436630
Hi. I think it deals more with the interaction of radiation with particles (or a particle) than with speed. At any non-relativistic speed (less than .1 'c' say) the wavelength would not be infinite or unbounded. Just my opinion.
19029
Sorry, but with the time you spent typing these questions you could of looked them up in your physics book or googled them.  Sometimes getting others to do your leg work isn't always the best answer to a problem.  Good Luck in your new class!
446040
The atoms' electrons absorb the energy (usually from the heat [flame test]). When they do this the extra energy causes the electrons to jump to the next energy level. They (the electrons) then loose the energy and fall back. In doing so give of a (depending on your book, or outlook) wave length of a certain frequency (light color). Or a photon of a certain color.\n\nGet an "A".
371019
Sorry, you're going to have to be a bit more specific than that. Electromagnetics is a rather broad subject.\n\n~X~
668913
Magnetic field has to do with the polarize charge of material, such as Iron.  \n\nIt is believed there is significant Iron near the center of the earth and yes rotation will cause the charges to align and thus create a magnetic field.  This is called the "Dynamo Theory".\n\nJUST BEING IRON DOES NOT MAKE THINGS MAGNETIC.\n\n"Previous theorists have assumed that the entire Core (or the Inner and/or Outer Core) rotates as a single flowing object within the Earth. If that were the case, then all of the charged (ionized) Iron material  would follow a relatively circular path around a single axis that we could call the Magnetic Axis. Basic Physics tells us that when electrical charges follow a closed (relatively) circular path (which is effectively a current), a magnetic field is always created as a result. The measurable evidence of this scenario would be a simple "dipole" magnetic field, with a single North Pole and a single South Pole, geographically exactly opposite each other on the surface of the Earth."\n\nSo if this theory where correct the Earth stopping it's rotation would in allow the magnetic field to fad.  But there are major problems with the theory.  For example it is known that the magnetic poles have flipped (Switched places) several time in Earths past.  Will if we have magnetic poles because of the earth's rotation to switch poles we'd need to reverse the cores rotation.  This would be an ungodly amount of energy.  There is nothing known that would do this once let alone a number of times.  And even if something could do it, we should have seen signs of the massive damage that would have resulted with these forces in play, like the Earth falling apart.   But in fact the poles shifting seems to be a pretty peaceful process on a planetary scale. \n\nAnd that is only one problem with the theory.  This is actually a very, very complex subject and there really is no way to know what effect the Earth stopping would have on the magnetic fields.  But I have attached a link to a very good article on the subject and it's pretty easy reading (Keeps the scientific jargon down and uses layman terms.)\n\nOthers are correct tough in what holds us to the Earth is gravity, not magnetics.  So it's the Mass (How big and dense it is) that keeps us here.  And rotation actually wants to make thing's fly away from it.  So we stay because the Earths gravity overcomes the acceleration.  So the acceleration of 1000mph is actually always enacting upon us, making us want to fly off the planet.  So stopping the Earth will not make us fly off as others have posted.\n\nThink of the spinning rids at the fairs and theme parks.  When you spin you are thrown away from the axis, the best example is the cylinder you go in and stand up against the wall.  When it spins your back is pushed against the wall, even as it turns so you are now spinning vertically like a tired, instead of horizontal like a top.  But when they stop the ride you don't go flying out.  That's because the wall holds you in and your move with the ride.  Well gravity acts like the wall and you move with the earth.\n\nYou would go flying of the earth if it continued to rotate and the gravity field somehow disappeared.
525277
well, the answer to this is simple.\nthis is because at infinity we assume the p.e of any body to be 0, as force is 0.\nAt distances lesser than infinity (i.e, in vicinity of attraction) the p.e will be lesser( energy decreases with decrease in distance) , which will obviously be negative.\n\ni guess that will help
282890
There are two answers to this question:  one, how the waves themselves propogate and two, how the wavefront moves.  \n\nTo answer the first there are two things to remember:\n1.) a changing magnetic field creates an electric field\n2.)likewise, a changing electric field creates a magnetic field\n\nWith those two things in mind, here is how an EM wave (of which light is just one type) propogates.  A changing electric field induces a magnetic field, which induces an electric field and so on as the wave moves.  In other words one creates the other to move the disturbance along and the fields "bootstrap" themselves forward.\n\nAs to the second part, the way the wavefront moves depends on the geometry of what you're looking at.  If you imagine a source out in space, then yes you could consider the wavefront as being a sphere whose radius increases at the speed of light (for a repeated signal, then you'd have concentric spheres, one wave for each time the object sends out a pulse).  However if you restrict the wave to move in something (e.g. a waveguide, or channel)  the wave fronts would look different.\n\n\nI hope that helps
588781
when the magnetic needle (a magnet) is places close to any metal, the magnetic field generated by the magnet will cut the metal and causes some electron to move inside the metal, which causes to metal to have different electric charge at each end. now because there is electric charge, it causes an electromagnetic field (EMF). this newly generated EMF interacts with the magnetic field created by the magentic needle and causes it to reflect.\nI remeber doing a physics experiment that illustrates this same effect. we had two small synlindrical metals, one of them was metal the other just normal metal. we put each one of them seperatly from one end of a metal tube and let it fall through to the other end, the metal usually gets from the other side quickly because it is falling free fall in the tube, however, when we put the metal inside it, it took much much longer time for the metal to fall through, the reason, as the magnit is moving (falling down) inside the tube, it is generating a current in the tube which in tern creats a magnetic field which opposes the magnetic field created by the magnet therefor the magnetic field creats a force that tried to repel from the falling magnet and it creates a force that tries to push the magnet up in the tube, of course the gravity is stronger and eventually the magnet comes out from the other end, but it didn't fall a free fall therefor it came out late..\n\nI hope this helps.