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1d
comment Physics without time
"obviously"? I don't agree that a photon must have a rest frame, nor that if it did it would have the properties you describe...
1d
comment Starter's book on Quantum Mechanics (more general and simple books than full QM textbooks)
@LandosAdam it's possible I haven't read his quantum mechanics book closely enough and that it's much worse than his mechanics book, I'll take another look over it tomorrow at a library.
1d
comment Starter's book on Quantum Mechanics (more general and simple books than full QM textbooks)
@LandosAdam I haven't gone through his Quantum Mechanics book in much detail, but I know for sure his mechanics book is absolutely academic physics (from after the principle of least action). If you go to a bookstore, pick up the QM book, and can prove almost every major result in his book, then you're right: don't get it. Otherwise, you might be too critical.
Mar
23
comment Kepler's Laws to Determine Radius of Circular Orbit
Try plotting $r^{-2}-r^{-1}-0.01\cdot r^{-3}$ instead. The correction is small. $c^{-2}$ is small.
Mar
23
comment Similar effect to gravity horizontally?
Your calculations are wrong (you set force=energy, which is like saying "my clock reads five meters" - it doesn't make sense!) And your units are incorrect (your speed is a measure of acceleration). Are you expectong someone to fly towards the back of a moving truck when they jump? This is incorrect! If you jump on an airplane you notice nothing special different than jumping on the ground.
Mar
18
comment Insight into Torricelli's Equation ($v^2=u^2+2as$)
@pdmclean so that's the meaning of Torricelli's equation! It is an expression of conservation of energy and what it shares in common with Torricelli's law is that they were both formulated by the same person.
Mar
17
comment Water Waves in the Wake of a Boat
I don't think this is the case. Ex. i.stack.imgur.com/PaSas.jpg seems to have no asymmetry and the lines of constant phase (or maximums if you prefer) still bend outwards!
Mar
16
comment wave equation for a homegeneous prism object
In the 3 dimensional case, any serious book on optics shohuld include it. The key topic here is the Fresnel equations: en.wikipedia.org/wiki/Fresnel_equations keep in mind these equations are for solving the wave equation in three dimensions. The two dimensional case will be simpler.
Mar
15
comment Is there any theoretical limit to the distance at which particles can remain entangled?
1. there is no theoretical limit to the distance at which particles can remain entangled. 2. Quantum entanglement cannot be used for instant communication at a distance.
Mar
14
comment Why 'Force x displacement', and not momentum to measure energy?
relevant: en.wikipedia.org/wiki/Vis_viva#History
Mar
13
comment How can shadows ever be sharp?
The short answer (ignoring Huygens principle and thinking of light like waves on a pond) is that frequencies of $10^4$ Hz end up being a totally different ball game than frequencies of $10^{14}$ Hz.
Mar
12
comment Commutativity and symmetric property in tensor manipulation
watch your upper and lower indices! It's also not true it equals $1$. See property 18 on mathworld.wolfram.com/MetricTensor.html
Mar
9
comment Ising model Monte Carlo simulations in 4D and 5D
To prove user37496's statement, consider choosing three axes from your set of four axes. Three defines a volume, so the number of (N-1)-hyperplanes mutually perpendicular passing through a point is $N$ choose $N-1$, that is, $N$.
Mar
7
comment Curl of Electrostatic Field
It's not true that an integral being zero means that the integrand is zero, but generally if an integral is zero for ANY domain, then the integrand is zero. So I feel like your answer isn't good.
Feb
28
comment Why is the relativistic Lorentz factor defined this way?
physics.stackexchange.com/q/114372
Feb
24
comment Rolling w/o slipping - does a friction force acts in this scenario?
Say you're holding a tire connected to an axle and you spin it up so that it's spinning at, say, one revolution per second. Then without yet letting it touch the ground, you get on a truck and accelerate at a velocity where you travel one circumference length of the tire every second. When you drop the tire, its angular momentum and momentum both do not need to change at all. So the ground doesn't actually have to exert any tangential friction force at all. Does this image help?
Feb
11
comment Is what i think Magnetism is, Magnetism?
Nope! Mostly wrong. A magnetic field stores energy, but never comes alone in a + or - alone. It's true that if you put one magnet into the field of another magnet, you put it in a higher energy state and have to use power to put it there, but it's not really the "power of the magnet" that makes it try to move back. See also: m.youtube.com/watch?v=qjmtJpzoW0o
Feb
10
comment Do the integral forms of Maxwell's Equations have limited applicability because of retardation?
@yashar You have a surface $S$ and its boundary $\partial S$. One integral is $\oint_{\partial S} {\bf B}\cdot d{\bf \ell}$ and the other is $\iint_{S} \dot{\bf E}\cdot d{\bf A}$. You can't change the bounds of one without changing the bounds of the other.
Feb
10
comment Do the integral forms of Maxwell's Equations have limited applicability because of retardation?
@yashar I don't know what you're saying. You're not saying that the $\iint\dot{\bf E}\cdot d\vec{\bf A}$ integral will be zero, correct? If you reduce the surface to be too small then the $\iint\dot{\bf E}\cdot d\vec{\bf A}$ integral bounds will change and the RHS will no longer be zero, so it's not OK to bring the loop inside the nonzero B field and have the RHS quantity be zero.
Feb
9
comment How do I correctly introduce time into this equation?
Much better than my (wordy) answer!