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Apr
20
reviewed Approve Projectile motion of a grenade
Apr
20
reviewed Approve If I repeated a quantum measurement, would it be the same?
Apr
20
revised Is the particle reaction $π^- + p \to K^- + Σ^+$ possible?
(v3.141: some copy-editing; while continuing to wait for PSE-MathJax to support rendering of pstricks commands ...)
Apr
19
answered Is the particle reaction $π^- + p \to K^- + Σ^+$ possible?
Apr
17
reviewed Approve Electrons moving in a simple circuit with a battery and a light bulb
Apr
17
comment Binding energy per nucleon in radioisotopes of hydrogen
@Saprativ Ray: "[...] elaborate on "the binding energy per nucleon is not necessarily the full measure of whether a nucleus is stable or not."" -- For example, tritium decays by a weak process. "what the values of binding energy per nucleon actually imply?" -- Comparison to all individual nucleons being separated from each other. (Btw.: yet another/more relevant notion of "stability" is: Which nucleus is the most resilient against gamma-induced fission?.)
Apr
17
reviewed Approve If I spinned a fan in a vacuum it will keep spinning forever. Why can we not make energy out of it?
Apr
17
reviewed Approve is there any way to create electric field around two similarly charged plates?
Apr
17
comment Why positron emission is unlikely to occur for nuclei with an excess of neutrons?
@dmckee: "Follow the logic. [...]" -- Logic allows at least to fill in the blanks you left: "Positron emission can only occur when a _$p$_ is converted into a _$n$_ inside the nucleus" -- (That's by plain charge conservation; a gimmee.) "but in a neutron rich nucleus adding a _$n$_ takes more energy than you get from removing a _$p$_ so [...]" -- So the presumed logic holds. But why does converting $p$ to $n$ in an already $n$-rich nucleous take more energy than the reverse?? (Why "valley of stability" rather than "ridge of instability"??) And: Does the OP ask this question?
Apr
16
revised Why positron emission is unlikely to occur for nuclei with an excess of neutrons?
title: spelling corrected
Apr
16
comment Why positron emission is unlikely to occur for nuclei with an excess of neutrons?
@Farcher: "Possible duplicate? Why beta+- decay occurs?" -- Not really: at least the OP question title implies an inquiry to justify, roughly, "why there is a line/valley of stability in the isotope chart (rather than, say, a line/ridge of instability)". However, admittedly, this request is not (yet) spelled out in the OP question text.
Apr
16
reviewed Approve Does AC-current reverse direction only in the main circuit (the powerplant-to-powerplant circuit)?
Apr
15
revised How to express in terms of spacetime intervals the average speed of one participant having moved between two suitable others
(v3.141592: making the transparancy wrt. possible "sign conventions" more ... transparent.)
Apr
14
revised How to express in terms of spacetime intervals the average speed of one participant having moved between two suitable others
(minor copy-editing)
Apr
14
revised Interpreting the Cross Section Ratio R
(still minor copy-editing ...)
Apr
14
answered How to express in terms of spacetime intervals the average speed of one participant having moved between two suitable others
Apr
14
answered Interpreting the Cross Section Ratio R
Apr
14
comment Acceleration of particle “held in place” at $x = 1$
jld: "Did you invent this notation yourself or did you get it from some other source? If the latter please forward it" -- Gladly; see my recent comments there. "the question as posed assumes that lengths are dimensionless. [...] So you could say the question was expressed badly." -- That's what I was trying to point out. Of course, my complaint is therefore not only to OP writer @user265817 but also to those responding without being critical; and, to be fair, surely to certain people who inspired such a badly expressed question being asked.
Apr
14
comment How to express in terms of spacetime intervals whether two participants in a flat region were at rest to each other
Finally (I suppose): I don't know any precedence, other than my own writing, for the notation of events (i.e. the arguments of the spacetime interval funct) I used above (which explicitly lists the participants having been coincident). However: it aims to adhere explicitly to Einstein's prescription that "All our space-time verifications invariably amount to the determination of space-time coincidences {such as} meetings between two or more material points".
Apr
14
comment How to express in terms of spacetime intervals whether two participants in a flat region were at rest to each other
The use of square brackets for enclosing (a comma-separated list of) arguments to a function corresponds to Mathematica (TM) style (StandardForm); see e.g. mathematica.stackexchange.com/questions/20166/… (Btw., this notation style allows to reserve parentheses for the purpose of grouping alone.) [... continued]