#general-2
1 messages · Page 226 of 1
yes, what might be confusing is that the formula you got there does not include a variable for time as it is - your friend just added it in the derivative and put its value in there
Yeah so can I consider dx/dy a legit value I can use algebraically?
dr/dt is the variable for time?? Like it doesn't need a t in the original equation
Yeah
If you know what (dy/dx) is equal to you can plug it in
yeah, but there was never a dt anywhere in there
Consider dx = dt
You use it when finding the derivative when time is involved
of course, that's what i meant with "his friend just added it and put its value in there"
Ok so
dy/dt=2(pi)r(dr/dt)
We know what pi is
We know what the rate of change of the radius is
Dr/dt is the rate of change of the radius
Rate of change is related to time
That's why there's a t
(Dr/dt) serves as one variable and once we know what it is we can plug the number in
i'm used to f(x) = .../ f'(x) = ... which is probably why i see it as a two-step thing
A two-step thing?
as in, you can't just form the derivative of f(x) by putting in a t
I'm not just "putting in a t"
i know
the (dy/dx) notation isn't just dividing variables and stuff
i know
Ok so what am I doing wrong then
nothing
How do you do rate of change problems? We might just be taught differently
yeah, that's kinda what i meant - i have never really been taught the (dy/dx) notation
Ohh ok
I can share my notes? They're a bit context based though :/
Wait actually
Ok let's say we want to take the Derivate of x^2+y^2=5
like f'(x) = t*2*x is not the derivative of f(x) if f(x) = x² (that's what i meant with "popping in a t")
I think the dy/dx is Newton's notation and f'(x) is Leibniz's notation
Oh no not like that
yes, Chessed
Ooh that's an interesting fact
Ok but
We have to find the derivatives in relation with each other
So that's kinda funny and probably the reason for this. Y'know, the English taking the English version and Germans taking the German one
the thing is - it's not really a divide like that
The derivative looks like this:
Newton's notation is used in most places - especially in physics
2x+2y(dy/dx)=0
I believe the whole equation is (f(x+h) - f(x))/h
We have to add a (dy/dx) wherever there's a y derivative to show that it's in relation to x
So
And dy/dx is just a shortening of that so you can save space
Ooh yeah that thing!!
All the rules stem from that
However
It takes a LOT of math to figure that out
Just google proof of the quotient rule
Yeah we went through it once
Like what the shit
hm, it's not that hard from what i remember
The rule is not hard
Anyways t is added because roc is in relation to time so the derivative is taken in relation to time
How they found that rule is the hard part
f'(x) = (u' * v - u * v') / v²
Yeah it's not I'm just naturally like this
yeah, and it is easier to add a relation to time with Newton's notation
with Lagrange notation you have to take another step - first form the derivative of f(x) and then make a new formula f(t) = t* f'(x)
It's easier to read/write though
Mmm math.
❤
Also the dx/dy comes from Leibniz actually.
🤔 i thought it came from 1/leibniz
Yeah, Newton notation is with dots above y
@sour mesa Do you know what always happens when the incident angle is 0?
no?
That's the angle of refraction, actually
How many refractions happen in this experiment?
Can you answer that?
I only see one
Which is?
But i've learned that if light goes out of a matter the refraction you get of that is the indicent angle and the angle in the matter is the refraction angle
And the refraction is the onda emergente
WHAT
but the arrows point towards the onda emergente
oh nvm
sorry about that
I mixed i t up
2 languages at the same time fucks my brain
so emergente means coming out
oh okay
but can you spot that it's not only 1 refraction happening?
So do you know what qualifies as a refraction?
When a light wave touches the area of a transparent matter, something happens: the light path changes. This is known as light refraction
sure
but that's not the formal definition
there's one requirement for refraction to happen
what's that?
so think of this situation
you shoot a laser from air to water
what's the one thing that's implied in that makes it garanteed a refraction
?
I think you got it
that's called medium
the transmission medium
not necessarily the change of trajectory, cause as you saw, in the exercise, when the wave goes from air to inside the block, it doesn't change it's angle
So in that case you have
Wave in the air -------> Wave in the Polystyrene Block --------> Wave in the air again
How many refractions happen there?
2
Great
But which one is the one that's gonna be helpful for you to figure out the refractive index of the block?
The last one, because that has an angle that is >0
nice
for you to apply the snell law and find out the index, which are the things you'll need?
∠r and ∠i
great
so basically from that on, I recommend trying to work with geometry
actually you need to
because you have to find the angles
I have figured out all the other angles of that triangle you get when you would split it in the dotted line
So what's the refraction angle?
I assume it's 0
are you sure?
remember the hint I gave you
Isn't that the dotted line?
Nope.
Oh that maybe why i was stuck
the dotted line is just there to be a reference to the 15 degrees
So
what's the definition of a normal line in optics
Is it the hypotenuse of the triangle?
Oh i think i have it
Okay
The line that is perpendicular on the matter's area
the angle between the onda emergente and the line N?
no wait
The angle between the middle line and the line N?
Let's review what r is
r is the angle formed between the normal line and the wave after the refraction happens
one of your answers was correct
which one? 😛
the second one?
Bad Nola
Yes.
oh now I see it, i looked wrong
so if the angle between N and the dotted line was x
what would be the angle of refraction?
x+15
great
so what do you need to do to find out the refraction angle, knowing that it's x+15?
I need to know x,
Yes
Now let's review the incident angle
the one inside the block
can you tell me where it is?
Isn't that one the angle of the hypotenuse above the dotted line?
Done. Next step?
one of them is wrong
angle i i suppose
yup
i is the angle formed between the incident wave and the normal line
the one you drew was the complementary angle to the normal line, which is 90 degrees
ohhhh
try again
Good job
okay, now it's all geometry
one thing that I didn't point out
in the exercise, it says that the onda incidente (incident wave) comes perpendicular to the block
That's correct
angle of hypothuse > adjecent = 65 degrees
angle r = angle i + 15
angle i = 180 - 65 - alpha
alpha?
You have this right?
yep
so, based on the definition of the normal line
what's the angle between the block and the normal line?
ohhh
😛
Okay
And angle r = 40 degrees
Okay
so
So now you have to apply the law
a sec
cause the exercise is only about understanding the logic
He rounds in the middle of an equation
but okay
using 0.65390430568 as sin40
or something
or just 0.6
okay
snell law
you're almost done
oh yea, and the refractive index of the air is 1
lemme write some fancy latex
okay
yeah 😃
If you have any more exercises just ping me, gtg now, will try to make them when I'm back.
Missed out on all the fun :(
Pois é
It is 😄
what do you think the essay is gonna be about tomorrow?
Is it tomorrow?
yea
tomorrow's ciencias humanas, linguages e redacao
Yeah hahaha
I know
At the end it's just an endurance test
not falling asleep while reading those texts
I must begin with my university physics and Thomas Edison Calculus books in the near future lel
nice
Thomas Edison Calculus? 🤔
Yes lol. There's no Edison in it. 😅
lmao
haha
Thomas is one of the authors.
George Thomas
Bergo doing the googling for me. ❤
If you want to learn calculus you don't need a text book really.
I learned last year it was awesome
By which I mean there is so much free maths stuff online.
And maths books are expensive as heck.
But you can if you want.
Just mentioning that it's not really as necessary as other subjects.
Limits are considered pre-calc, right?
From what I can see, they have a chapter on functions and limits and then they move onto the real stuff.
But meh, if you have a solid foundation, you don't really need much more than that.
I have a pdf for Calc 1 here if you are interested in it: https://notendur.hi.is/adl2/CalcI_Complete.pdf
Which is effectively the same content as: http://tutorial.math.lamar.edu/Classes/CalcI/CalcI.aspx
Got what?
Thomas Calculus
Oh right, I see. I thought you were planning to buy it.
Nah i already got jt

Yeah
Thanks
After i finish calc and physics i wanna study probability
I love how "applyable" it is
Why after?
I mean, studying many things at the same time is so confusing for me
I don't read 2 books at the same time
Okay. Well, I just wonder, because some physics depends on probability.
But you can always just learn it if you get to that point, I guess.
Just google probability physics book and youll see something
It covers p much anything
1.5k pages
Okay.
Hello people, mind if I ask a question?
Could someone explain to me what an "eignungsprüfung" is?
It translates to aptitute test, yeah, but what exactly is it?
Ah, it is for Fachhochschule Aachen, International Business Studies
in general it tests you on the things you should be able to do or should know for a certain thing
be it a profession, a task or whatever
I was looking at the "NC-Werte", and I can apply but it says "Eignungsprüfung erforderlich"
And there is no explanation for it actually
So it is not something I send with my application, when I get there I got to take the test
probably
but i can't tell you for sure since i don't know how they handle it there
you should try to contact them
I will have to call them on monday then, thank you very much!
Wow, I read pretty much everything on the website I don't know how I overlooked that
Thank you very much and sorry to trouble you! 😃
I hope so, thanks again 😃
I had a trivia competion where i had to answer a german language translation question
It was translate the name of the following song from German to English
"Das Lied von der Welt"
Hallo
hey
Wilkommen
Oh I'm not new lol
But I am
I mean ya but u were saying welcome to me lol
I have just joined
Hhhh
Ah ok well uh wilcommen then
or
Wilkommen
Whatever you guys spell it as
Sorry I don't speak German
No problem
Take it easy
So how is it going here
Mm not much really
Translate: She is being observed. @red pewter
tfw "observieren" is veraltet 😩
don't use it.
Sie wird beachtet :?
How do you guys do the weird text?
why did you choose beachten?
Observe=beobachten or beachten?
more beobachten
beachten... is a bit different
🤔
can work
what's the difference?
sure it's the first word?
depends on the context bell
lol
two can play at this game, chuck.
What do you think of betrachten, Solet?
betrachten works
🤷
but in this case it should be beobachten
okay, let me look at beobachten
What browser are you using, cbell? 🤔
it's more like "Look at, me!"
Oh, what
Sie wird beobachtet
Their search is terrible then 🤔
just observe gives you the actual translation
so just do observe :?
If you say something like "Wenn man diese Situation beachtet..." it's more like if you consider/take into account this situation
wow. that's terrible.
didn't know it worked that way myself
you gain 1 grammar point
Always click the word to see its more precise definition
it is
Can you not betrachten a person, Solet?
you can
or to view as
Yeah okay, it works the same as in Norwegian then
but strictly observing is beobachten
Any word starting with "be" in Norwegian we stole from you guys pretty much
cheater
PHASE 2
Translate: The video was uploaded.
Can we get some natives fighting over whether that's a separable verb or not? 😄
can beobachten be to pay attention?
I thought that was aufpassen :?
it's not
why shouldwe fight?
not really, berg
it can be implied
but not really
ah ok
Das Video wurde hochgeladen
Wie machst du das @red pewter

cbell: +1 grammar point
...I thought they were praising me on my beautiful sentence 😄
@pine ginkgo No? 🤔
PHASE 3
Translate: The incriminating evidence was being downloaded by the FBI when the power mysteriously cut.
I'm talking about uploaden
oh
Or hochladen
u thot dis wud b easeh
Der verfängliche Beleg wurde vom FBI heruntergeladen, wenn die Energie geheimnisvoll abgeschaltet hatte.
(RIP)
wenn 👀
heheh
That's the error you choose to point out? 🤔
😦
@cold vessel That's the first one I spotted tbh
btw bell
cbell, please change your main clause from simple past to present perfect. What you have (of that part) is fine but that was the real test. I should have been more specific.
if you looked at incriminating on dict.cc
you would also have found incriminating evidence
please use that translation
I didn't even see that 🤔
!!!!
TRANSLATION?
I saw that the one i had had [evidence] by it and was proud for noticing
What's the sentence? 🤔
wait so i need present perfect passive :?
also Belegis more like evidence for bills and invoices rather than evidence for crimes
yes please
PHASE 3
Translate: The incriminating evidence was being downloaded by the FBI when the power mysteriously cut. @ocean robin
ahhh
it's not an easy sentence
do you want to do the phases too?
belegtes Brötchen
oh okay okay
tbh
i think this might be a bit too difficult for them
at least to make it sound like a how a german would say it
perhaps I went too troll
Can I post my try then?
du darfst
oh shit
henbri is a cheater
he will probably do some dumb mistake, but otherwise have it correct with the grammar
henbri just waiting on the wings to take the grammar points
Ehh 👀
Das Belastungsmaterial ist vom FBI gedownloadet worden, als der Strom mysteriöserweise abgedreht worden ist.
subordinate clause was not passive
downgeloadet or bust
@cold vessel same tbh
yeah
herdowngeladen?
Das Belastungsmaterial wurde vom FBI heruntergeladen (worden?), als die Energie geheimnisvoll abgeschaltet hat.
shit just got real 👀
The incriminating evidence was being downloaded by the FBI when the power mysteriously cut: Der Belastungsmaterial war vom FBI heruntergeladen worden, wenn die Energie geheimnisvoll abgeschaltet hatte.
oops
oh
sorry.
Das Belastungsmaterial ist vom FBI heruntergeladen worden, als der Strom mysteriöserweise abgedreht worden ist.
sure
okay that sentence was too intense, so I will give you another chance to gain a grammar point cbell
Mine is like 99 percent similar to hembris
And what about me Pferd? Is it good or baddo? 🤔
no, I want to finish it
mine is a bit different :P
am I getting closer?
I would use ausfallen for cut
no grammar points for you @ocean robin
you have to start at first phase
Das Belastungsmaterial ist vom FBI heruntergeladen worden, als der Strom unerklärlicherweise abgeschaltet worden ist.
:(
The incriminating evidence was being downloaded by the FBI when the power mysteriously cut: Der Belastungsmaterial war vom FBI heruntergeladen worden, wenn die Energie unerklärlicherweise ausgefallen hatte.
i was proud of it though
@red pewter your passive is the past in the past
"past perfect", in more precise terms
Die belastenden Beweismittel waren dabei vom FBI heruntergeladen zu werden, als der Strom mysteriöserweise abgeschaltet wurde
ehehe
also remember that "wenn" (if you knew) is not used in the past tense except when meaning "whenever"
don't worry, if you don't get how this was formed
oh.
Das Belastungsmaterial wurde vom FBI heruntergeladen worden, als die Energie unerklärlicherweise ausgefallen hat.

the heckie is that
I don't get it 🤔
that's why it will be very difficult for you guys to do it like we do :D
don't forget we don't have a progressive tense
that's a different form of the passive
okay i guess this phase is over.
so we... have to be creative
I think?
yeah y'all do fun things with bei 😄
yeah not having a progressive is confusing
dw about understanding what i did
not enough to unlock the next 3 phases but she may retry phase 3
dw 
does she wish to retry?
And I have 0 points 
yes
what does dw mean @pine ginkgo
"deutsche Welle"
🤦
PHASE 3
Translate: His boyfriend has been arrested by the secret police.
dammit
Hehehehe
"His boyfriend" heh.
Sekretpolizei
🤔
translating progressives is just not an easy task for learners, keep that in mind pferd
especially in passive
In Norwegian we don't do all that weird stuff to get around not having the progressive, we just use the present and context 👀
so, does henbri's/my formulation sound unnatural or just not what you personally would do 🤔
we just have multiple ways of translating progressives
and sometimes doing it "simply" doesn't really cut it
what learners mostly learn is "ignoring" the progressive or add something like "gerade"
So how bad does "Das Belastungsmaterial ist vom FBI heruntergeladen worden, als der Strom unerklärlicherweise abgeschaltet worden ist." actually sound.
look at your notes, flops
Totally expected arrestieren to be a word 😐
why?
What do you mean "you can't"
Was pretty sure of that though...
for teeeis
Werden in present + pp + worden + infinitive? 🤔
nope
pp = paat participle eh
@pine ginkgo for which clause, since I'm pretty sure I used the same tense for both
D:
the first one
whaaaat
ok
Sein Freund wurde von der geheimen Polizei festgenommen
delete "infinitive"
RIP BELL
do you?
What's the current flap sentence
@red pewter that is Präteritum, please change to past perfekt
I thought luna said not :?
He was talking to Ari :P
Luna was referring to Ari's sentence
@ocean robin that says like "his friend will have been arrested" I think.
smart teeeis
yeah, I figured, no problem
Nooooooo D:
yeah, you wrote Futur 2 passiv, flops

@pine ginkgo shockingly, I know grammar. Unfortunately, I don't know what words to put into the grammar sometimes 
it's alright, your sentence is not wrong
just, shockingly
sometimes we do prefer preterite
I just meant in general 
Sein Freund hat von der geheimen Polizei festgenommen worden
shockingly wrong
maybe :?
Sein Freund wird von der geheimen Polizei verhaftet worden. 🤔
...past
and if you say no
ask before
the exercise is useless, if you don't know how to form the passives
idk lel
you should also take notes for this
@ocean robin flappy
you will do it forever until you know it
yes
your last sentence was grammatical but the wrong tense
but you took the wrong word out 
or german passiv
DAMMIT
My apartment had been searched by the police. :Meine Wohnung war von der Polizei durchsucht worden
is what i was trying to reference
Sein Freund wird von der geheimen Polizei verhaftet worden sein.
This is a correct future passive. You need to make that not future.
"Had been searched"
Which word makes futureness
change it from past perfect to present perfect, bell
Yes.
which sentence, luna?
Now, since we need to make "wird verhaftet worden sein" not future
what do we have to take out
🤦
NO
SORRY
I GIVE STRUCTURE
BUT I uh
My apartment has been searched by the police. :Meine Wohnung ist von der Polizei durchsucht worden
:?
We take out the flux capacitor, Ari.
yep
HILFSVERB FOR WERDEN + PP + PP FOR WERDEN
good job, bell
@ocean robin er wird lernen, er wird verhaftet worden sein
NOOO
That's the word that you need to get adiós
u wot
u wot
now apply that structure to my sentence @red pewter
eh wot
@ocean robin ok, in the simple sentence again:
ANSWER
er wird lernen > er lernt
SEIN
anyway, for both of you, flops and bell, if you don't have you notes or if you forgot how to form things
👀
WHY IS SEIN THERE? GIVE REASONING
there's the internet and google.
oh yes
or any other search engine
whhhhy 
His boyfriend has been arrested by the secret police: Sein Freund ist von der geheimen Polizei festgenommen worden
good, bell
LOL BING
😄
The person who reacted like that must get out. Now. Here's a door for you. 🚪
so it's always sein? I thought that was just because of the verb. I'm sorry for making the mistake
Ok flopsel, let's look at what you've done:
wird verhaftet worden sein - wird = X verhaftet worden sein, move the sein and conjugate it = ist verhaftet worden sein - so since we've moved the sein why did you keep it there too?! 
The data shows that that's you Flops. Now go.
yeah, bell

for present perfect and past perfect
You have two seins @ocean robin and you started with one
There should only be one sein
Eh, I edited the message.
inb4 deletes "ist"
:D
This reminds me of teaching math 🤔
Sein Freund ist von der geheimen Polizei verhaftet worden.
I think "geheim" and "Polizei" would be better if you make a compound noun out of them
lovyer Floop
But yes flap, structurally that is now correct
now that you have done the sentence, can you tell us the structure of passive in present perfect @red pewter?
yay finally
But yeah, use Geheimpolizei as one word and it sounds better.
okay
Sein Freund (🌈😄) ist von der Geheimpolizei verhaftet worden.
lol ari 
it's sein + perfekt + worden
Don't call it "perfekt"
lol sorry 😄 past participle.
"perfekt" is the whole tense
😄
but yeah
conjugated sein - past participle participle - worden
Ari is wise
Es ist gelernt worden!
You sure?
no, was a joke
what's a past participle participle Ari?

❌ Check failed. You probably don't have permission to do this.
Is it the secret Partizip 3
unfortunately, you have not gained a grammar point this time, but your efforts were commendable and I hope the passive will terrify you in your sleep, I mean, will be more clear to you now
Gewesen, gespielt, etc... = past participle
wOt
You know such illegal writing techniques shouldn't be taught in public
that's okay :33 may I have another please?
Pferd, PHASE 4
no
:(
only those with 3 grammar points may do phase 4
well, may I retry phase 3 :?
Do I have 3? 🤔
we can restart the phases and maybe you will both gain the necessary points
PHASE 1
Translate: The fox is being hunted.
i think everyone's at zero
😦
grammar points are gained by flawlessly translating the grammar of a sentence
word usage is ignored because hard
i deal with word usage
Der Fuchs wird gejagt.
pferd deals with passive shit


wtfff
we now wait for cbell
The fox is being hunted: Der Fuchs wird gejagt
:D
.
you both gain a grammar point
Das französische Füchslein wird von einem memigen Arrem gejagt.
WOOOO
Der heißer Typ wird nachgestellt 
Aber das impliziert, dass es einen unmemigen Arrem gibt
Discord accepts png's 😄
@nocturne spruce Den gibt es. In diesem Server aber nicht.
Ach so
:<
@nocturne spruce Ich habe Arrem in anderen Servern unmemig sein sehen. 😮
Gibt es mehrere Arrems?
inb4 flops oder ein anderes A-Niveau mich durch *gesehen "korrigiert"
Der Fuchs wurde von den Hunden getötet.
lol teeis
The fox was killed by the dogs. Der Fuchs wurde von den Hunden getötet
😦
riF flap
you both gain a grammar point
rip flapps
Is this how flops' story ends?
YAY
@shy bobcat Why is it sehen? 🤔
Or is that a completely different fox
@cold vessel double infinitive shenanigands
PHASE 3 - PRESENT PERFECT
Translate: Do not worry, the bell has been rung.
@whole rapids flops kann leider keine weiteren Grammatikpunkte sammeln, weil sie schon wegen der Hunde tot ist.
😦
😄
uh
guys
I still don't understand commands
imperative is on my list of "hey i suck at this"
i will google.
Sorgen* oder?
Mach dir keine Sorgen darum, sie wird wiederauferweckt werden
Masterful evasion of the imperative by flops
Sorgen
:>
Isn't it Sorgen
It is
shiet by the way
but that's beside the point
I was taught "keine Sorge" 🤔
brutal
Lel
I guess "keine Sorge" would work in the same sense that "No worry" works
But there's also the "mach dir keine Sorgen" eh.
It is wrong, but passable
?
In other words, it doesn't work 👀
It does
:>
It does?
Oh really
Well, if it actually does ok
Do not worry, the bell has been rung: Mach keine Sorgen, die Glocke ist geklingelt worden.
