2d
revised Problem on circular motion
added 404 characters in body
2d
revised Problem on circular motion
added 526 characters in body
Jul
18
answered Problem on circular motion
Jul
17
comment Dyson Series Iteration - Gives Exact Solution?
@Electrictobe Not quite sure. (Read this: en.wikipedia.org/wiki/Dyson_series ) It looks to me that the main message of dyson series was to take care of the deviation of operator's time dependence. By increasing the order, it resolves the time dependence, and when approach infinity, it's exact. It's basically integrating along the path in infinite decimal place in $t$. It doesn't matter which operator you are using, as long as it can be expressed as a valid dyson series, which is important, you don't need to worry about the solution, unless you are thinking about approximation.
Jul
16
comment Integral as summation in quantum mechanics
@kay when you convert $\langle f|g\rangle $ to $f(x)g(x)$ you probably used summation of $|x\rangle\langle x|$ over all $x$, which is equivalent to $\int_x dx |x\rangle\langle x| $ because $x$ was over $R$, I guess you may consider that's where it comes from.
Jul
16
answered Dyson Series Iteration - Gives Exact Solution?
Jul
16
revised Confusion with identity operator
added 24 characters in body
Jul
16
answered Confusion with identity operator
Jul
16
answered Integral as summation in quantum mechanics
Jul
14
answered Do objects besides strings, ropes, and rods have tension?
Jul
14
answered Lorentz transformations: new actual notation for a $4$-vector
Jul
9
accepted How to prove the law of equal action and reaction?
Jul
7
comment How to prove the law of equal action and reaction?
But as you pointed out, if the force is conserved, we can show the law of equal action and reaction as a "result". Is there way to bypass the restriction in unconserved cases? I mean, the definition of force was independent of the "law" itself.
Jul
7
comment How to prove the law of equal action and reaction?
Thank you. $F=ma$ was known, I want to prove that $F_{ba}$ exist and that $F_{ba}=-F_{ab}$.
Jul
7
asked How to prove the law of equal action and reaction?
Jun
30
awarded  Organizer
Jun
30
answered Rotation of Rigid body
Jun
20
accepted Why do some people write the gravitational force as proportional to $\mathbf{r}/|\mathbf{r}|^3$?
Jun
19
awarded  Popular Question
Jun
19
asked Why do some people write the gravitational force as proportional to $\mathbf{r}/|\mathbf{r}|^3$?