The h Bar

aww

Pissed off layman

:-/

Nice comment @EmilioPisanty

Emilio Pisanty

@Pissedofflayman yeah, TLDR Legal is awesome

@Sanya WaybackMachined for later reference. That one's golden but it will rightfully go the way of SE's automated vacuum cleaner.

3

@Kenshin, i really hope you're not serious on the aerosol can question.

gtg, have a good day all.

12:13 AM

@heather you think so?

no, i'm just confirming

lol

na just kidding of course

=)

laterz @heather

@EmilioPisanty that's a good idea - even though I'd like an "archive of weirdest questions" or "archive of bad question stereotypes" :D

thanks =)

12:14 AM

yay its immortalized =D

(nearly, anyway.)

Loong

@Sanya gemsfromstackexchange.tumblr.com

@Loong yep, sth like that for physics only :D

12:30 AM

i just did an experiment and got outcome a. i'm also reading a paper where a scientist did the same experiment but got the opposite of outcome a. any suggestions?

repeat the experiment and search for more sources?

the sources have been just as confusing. :-( out of 7 sources, 3 got outcome a and 4 got outcome b. i've repeated the experiment a few times and its always a

eh

i'll just flip a coin or something

but this is a perfectly fine result

you can quote those seven papers, describe your experimental setup as well as possible and describe your results

then I'd think about possible influence factors that might not be controlled and might influence the outcome

furthermore, maybe you can try to identify differences in the experimental setups described

but in the end, your results are perfectly valid and quoting all the literature is the most scientific thing to do

i'll do that.

thanks for your help

sure =)

user228700

12:41 AM

@DanielSank I'm not too sure about "far more pressure" but there is a great deal of pressure, yes. Ask @Secret.

HalO KAumu

yes I think India would have more pressure than USA

user228700

Hey, @Kenshin: :-) Yeah, perhaps.

do u celebrate new years eve @Kaumudi.H

ohh god new years soon

and personal growth

yeah like tmr

12:44 AM

how???

time flows man

too true

we don't have time machines yet, physicists need to lift their game

@Kenshin maybe you could do it

i'm not a physicist

I'm a samurai can't u see

12:47 AM

didn't you build a time machine to get here?

yeah but that was invented in the future

by someone else

the nobel prize you received should convince me otherwise

u know about that?

yes

i am from the future

anyway i have to return to my bathroom lab

ok catcha later

12:50 AM

goodbye samurai from the past

sayonara

user228700

@Kenshin Nope.

user228700

I'll answer in detail in a bit. For now, I have a quick question.

oh

yeah go ahead

user228700

For quantities whose magnitude is determined by the dot product b/w two vectors (eg: Work), what is the minimum value? Let the two vectors in question be $\vec{a}$ and $\vec{b}$. Is the minimum value 0 or $-|\vec{a}| |\vec{b}|$ ?

user228700

12:56 AM

(I'm asking about the general convention here)

is there a context?

it would depend on exactly how the question is asked

e.g. if it said what is the minimum magnitude, or minimum absolute value I'd say 0

if it said was the minimum value of a.b then I'd say -|a||b|

but generally "minimum" means most left on the number line so without context I'd have to say -|a||b|

user228700

That makes sense. Well, okay, if I were asked to find out the minimum value of work done on an object, given the force applied and the displacement of the object, would that be 0 or $-|\vec{a}| |\vec{b}|$ ?

hmm

that would be a weird question

is this actually a question?

because if the force is in the opposite direction to the displacement, how is the object even moving?

user228700

Therein lies the confusion.

and if the force is perpenduclar to the object, again what is causing the object's displacement to change

user228700

1:02 AM

@Kenshin Lol, um, I remember that when I was in high school, we had a question like this, with the magnetic field doing work on a charged particle...well, um, no, not the magnetic field, but uh, dang it.

user228700

I did have a question like this tho :-/ I just don't remember any of the details. All I remember was all of us nerds arguing about whether the answer is 0 or the - thing after the exam.

user228700

And it turned out that our teacher had wanted us to write 0 but yeah, what to do in such cases?

was it multiple choice?

in such a case I would give both answers

I'd say the minimum value is -|a||b| while the minimum absolute value would be 0

user228700

Ur answer would be marked wrong if u give both answers. It's an OMR sheet.

is that multiple choice?

user228700

1:04 AM

i see

I can only hope that the question did give some clue to differentiate between 0 and -|a||b|

user228700

Alright, I will ask more people here and see what the general opinion is. Thanks :-)

np

1:41 AM

w00t, uploaded a package to CTAN.

user228700

2:13 AM

I come with a homework question. Given two vectors $\vec{a}$ and $\vec{b}$, I've been asked to find the component of $\vec{b}$ in the plane of $\vec{a}$ & $\vec{b}$ but also perpendicular to $\vec{a}$.

@Kaumudi.H ok...

user228700

I couldn't figure it out on my own so I caved and checked the solution after trying for a little while and the solution has given the answer as $\vec{b} - \{(\vec{a}.\vec{b})/a^2\}.\vec{a}$

Yeah that looks right.

user228700

I don't understand how...

A considerably easier way to write it is $$\vec{b} - \hat{a}(\vec{b} \cdot \hat{a})$$ where $\hat{a}$ means "unit vector in the direction of $\vec{a}$".

user228700

2:17 AM

Yeah...

user228700

Gimme minute.

Well, what have you figured out so far?

user228700

Well, $\hat{a}(\vec{b} \cdot \hat{a})$ gives the component of $\vec{b}$ along $\vec{a}$.

user228700

No, wait.

lol

Ok, I won't give hints.

user228700

2:21 AM

:-| I was correct. That does give the component of $\vec{b}$ along $\vec{a}$.

yes.

user228700

I'm trying to figure out how subtracting this vector from $\vec{b}$ gives a vector that is perpendicular to $\vec{a}$.

If I have no component along $\vec{a}$, then I'm perpendicular to it by definition.

user228700

Ohh, right :-/

Try computing the dot product of $\vec{a}$ and $\vec{b} - \hat{a}(\vec{b} \cdot \hat{a})$.

user228700

2:28 AM

Yup. Zero.

user228700

It didn't occur to me to actually remove the component of $\vec{b}$ along $\vec{a}$.

koolman

Good morning :-)

user228700

Wokay, @DanielS: Dhanyavaad :-)

user228700

@koolman G'morning :-)

Q: Why does delocalization of pi electrons bring stability?

@Kaumudi.H ?

@Kaumudi.H With vectors, one can be rather brutal.

user228700

2:31 AM

@DanielSank Lol :-P Dhanyavaad = Thanks in Hindi.

user228700

You gots to know at least that much if you plan on visiting someday :-)

user228700

Huh. Where did @MAFIA go? :-o @user276738: Oh, is that you? Were you the one who asked this question:

user228700

3

My book mentions that Delocalization of $\pi$ electrons makes a compound stable as the process of delocalization involves loss in internal energy. This is the synopsis of resonance. But how does shifting of $\pi$ electrons let the body lose internal energy? What is the cause? While studyin...

organic-chemistry resonance formal-charge

user228700

I recognize your dog :-) Which textbook is it?

@Kaumudi.H Bah. I'll learn it later.

I'm doing Russian now.

When I get ready to come to India I'll cram Hindi for a while.

user228700

2:41 AM

Ah, okay.

But I'll have a horrible accent.

user228700

Obviously :-P

I can imitate accents well but I need to hear it.

I don't know anyone who speaks Hindi.

user228700

YouTube!