Note: I'm not sure how tolerated this is elsewhere, but the Physics.SE community seems to be fine with it.
Depends. I usually use
4) Write an "extension" answer, referring to the original answer, adding the relevant data.
I generally think its impolite to make major edits to an established user's answer. Also, my addendums usually go way beyond the scope of the other answer.
General rule of thumb:
- If its just a bit of more info (read:a paragraph), add it and leave a comment.
- If it's a completely new bundle of stuff, but is based on stuff gleaned from the answer, write an addendum answer as described above. Hat it with "This is in addition to @JonSkeet's answer". You may also comment on the original answer and ask the poster to incorporate your answer if s/he wishes--and then delete your answer once the deal is done (Something smilar could have happened here, though it didn't).
Factors affecting torque and RPM of a motor
How can one imagine curled up dimensions?
Penetration versus Frequency
Will an emf be induced across the ends of a stationary metal rod placed in a time-varying magnetic field?