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Apr
20
awarded  Nice Question
Mar
6
comment Where's the energy in a boosted capacitor?
I'm sorry I still don't understand what were you trying to say in your second last comment, after re-reading it several times. Thanks for the paper, actually I already know about stress tensor. I'm just trying different approach here.
Mar
4
comment Where's the energy in a boosted capacitor?
@LarryHarson yes I think it's somewhat clearer that way. I've modified my answer to include that, thanks for the suggestion. I have rechecked it again, I still think that event 1 happens before event 2. The rule of thumb is "rear clock ahead."
Mar
4
revised Where's the energy in a boosted capacitor?
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Mar
2
answered Estimate number of hairs on human head
Mar
2
revised Practical method to weigh human limbs with common household items?
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Mar
2
comment Practical method to weigh human limbs with common household items?
@0xC0000022L Hey I made stupid mistakes in my previous answer, sorry for that. I've updated my answer with an "uglier" one.
Mar
2
revised Practical method to weigh human limbs with common household items?
added 1897 characters in body
Feb
27
comment Whistle Physics
Yes it is a kind of vortex shedding. Perhaps this is what you are looking for? www2.ibp.fraunhofer.de/akustik/ma/pipesound/animEdgeTone.mpeg
Feb
27
revised Practical method to weigh human limbs with common household items?
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Feb
27
answered Practical method to weigh human limbs with common household items?
Feb
27
comment Where's the energy in a boosted capacitor?
I'm not sure where my argument is flawed. The same conclusion can be reached by calculating the momentum of the rod and using the fact that the rest mass of the rod is zero to calculate the energy of the rod in the boosted frame.
Feb
26
comment Where's the energy in a boosted capacitor?
There won't be any physical change happening on the capacitor during this changing process. The only thing is that the energy/mass that was hidden in rod 1 is simply transferred to rod 2. The purpose of changing rod is just to determine the amount of energy hidden inside the rod. The rod is part of the system and we need to include it in the energy calculation.
Feb
26
comment Where's the energy in a boosted capacitor?
I think it is not quite a problem, we can always recreate the starting condition. Suppose that initially there is already a rod between the plates, call this rod 1. Then at $t=0$, this rod suddenly disappears and rod 2 suddenly appears to replace it. From the point of view of the rest frame of capacitor, doing this won't change the energy of the system. And thus it must be so in any other frame. In the moving frame, rod 2 does not receive work from the left plate and the right plate simultaneously. Thus some energy is transferred into rod 2. And this energy must be taken into account.
Feb
26
comment Where's the energy in a boosted capacitor?
I was't saying that the capacitor is accelerated. I mean the plates are attracting each other through electrostatic forces, so if there is nothing that counters these forces(i.e. a rigid rod) the plates will crash into each other. Now if there is a rod between the plates everything looks the same as in the problem description, I know that we are just viewing it in a moving frame. But the rod plays a role here. In the frame where the capacitor appears to be moving, the rod does work on the capacitor. And the total work turned out to negative, as a result the rod's mass is increased.
Feb
25
answered Where's the energy in a boosted capacitor?
Feb
24
answered Whistle Physics
Feb
24
awarded  Popular Question
Feb
23
awarded  Informed
Feb
22
revised What happens to the magnetic field in this case?
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