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Aug
22
comment Why is static friction called self adjusting force?
I actually think this is a good question. Perhaps keep the title, and allow the question to be "I have heard static friction called a "self-adjusting force". How can this be? How does the force "know" how large to be? They way I understand it....".
Aug
1
reviewed Reviewed Shallow water wave question from Acheson's book
Jul
31
revised Problem with shell model and magnetic moment of Lithium-6
Just added math tags.
Jul
31
reviewed Reviewed Problem with shell model and magnetic moment of Lithium-6
Jul
31
suggested suggested edit on Problem with shell model and magnetic moment of Lithium-6
Jul
27
comment What strategy should I use to approach this problem? If my straight line approximation doesn't work
This answer is very close to what my comment was getting at. The equations (2) and (3) are the equations of the lines touching the steps. You have in your diagram equation (3); equation (2) is parallel to the steps but touches the upper corner of each step rather than the lower corner, which (3) does. You "derive" them with the equation for a line $y=mx+b$, where $m=1$ and there are two different $y$-intercepts, $-99$ and $-100$.
Jul
27
reviewed Reviewed How do I calculate motor efficiency from voltage, current and RPM?
Jul
27
comment How do I calculate motor efficiency from voltage, current and RPM?
"Useful work" is whatever is possible to get out of the motor, not what is actually gotten out of the motor. At least, that's a reasonable interpretation. The efficiency of a motor should not suffer just because you forgot to hook it up to something right?
Jul
26
comment What strategy should I use to approach this problem? If my straight line approximation doesn't work
I think you want to find the intersection of your equation for the motion of the projectile (assuming it's correct...) with the equation of a line starting 1 foot before you have the line in the diagram - meaning, "at the top of each step" instead of at the bottom. Then you can be sure of which step you land on.
Jul
26
reviewed No Action Needed Relativity of simultaneity example in Resnick
Jul
25
comment How to calculate the 2-point function of gravitons?
Ok well you might just be reduced to checking out arXiv articles until you find one that references something. Check out Brandt and Frenkel from 1993, they seem to use Birrel and Davies "Quantum Fields in Curved Spacetime" - you check that one out yet?
Jul
24
comment How to calculate the 2-point function of gravitons?
The graviton does not exist in "GR", it only exists in QFT. I seem to remember that Peskin and Schroeder has a section on it, but just check out some of the more extensive QFT textbooks (Weinberg maybe?)
Jul
24
reviewed Reviewed Mass generation by Chern-Simons theory
Jul
23
reviewed No Action Needed Pool in a submarine
Jul
22
comment What is the path integral exactly?
I won't downvote but it does seem like "a poetic description of a mathematical device" is pretty unclear. The path integral is not poetry, so it must be the mathematical device? So what is the poetry? Path integrals describe reality to $10^{-9}$ (or whatever); they must be more than poetry!
Jul
22
reviewed Reviewed How do I know which force to use in moments calculation?
Jul
22
comment How do I know which force to use in moments calculation?
I totally agree with ACuriousMind, but maybe you can answer your own question with some intuition - pick one of the situations you are confused by and consider it as a 'real life situation', rather than an abstract problem. Which forces would you expect to cause movement? These forces need to be accounted for when finding the static condition.
Jul
22
reviewed No Action Needed Why do bubbles make a sound?
Jul
21
comment If light was able to pass through a wall, would the wall be invisible to the human eye?
Make sure you understand what you mean by "light" vs "radio" - both are photons, part of the electromagnetic spectrum, and both can pass through some walls but not all walls. Maybe some clarification on this point will help. It sounds like you have a specific case in mind; share it with us?
Jul
21
reviewed No Action Needed If light was able to pass through a wall, would the wall be invisible to the human eye?