The h Bar

Muhammed Ç. TUFAN

00:00

Hmm

What is the domain of function $\tan\theta_1(\theta)$?

And the value range of $\theta$?

ACuriousMind

That doesn't really matter - you can't use anything after the step you multiplied with $\frac{V'_i}{V'_i}$ for the case $M_1 = M_2$.

What your teacher did yields the correct result, but not in a rigorous way

Muhammed Ç. TUFAN

Hmm, you mean It's 0 and It's impossible..

The $\theta$ is $\pi$ thats OK.

ACuriousMind

The reason your teaching did that trick is that the equations alone don't really tell you a unique outcome for that case

Muhammed Ç. TUFAN

What about the $\theta_1^{\max}$?

ACuriousMind

It is consistent with the equations for conservation of energy and momentum that the first object just passes through the second without anything happening, i.e. the equations alone cannot tell you that $\theta = \pi$ and not $\theta = 0$.

We need to use common sense to deduce that $\theta = 0$ is a nonsense solution (balls don't pass through each other)

Muhammed Ç. TUFAN

00:07

Hmm, okay I get what you mean

ACuriousMind

The proper argument for what your teacher did would be to argue that $\theta(M_1/M_2)$ needs to be a smooth function on $(0,\infty)$.

Muhammed Ç. TUFAN

I don't know teacher did draw graphs of the situations

It's really hard to understand by me :/

ACuriousMind

And if you take the limits $M_1/M_2\to 1$ from below and above there, you'll find they both yield $\theta = \pi$, so for smoothness you need $\theta = \pi$ and not $\theta = 0$.

I feel I could explain this better if it wasn't 1 am ;P I'm going to go hit the sack and think about how to explain this properly.

Muhammed Ç. TUFAN

Okay, I trust you

I took that lecture today

And when I arrive home I started to think on this

Everything was perfectly going good while the teacher telling but at the last 15 minutes he messed up everything

:D

Nevermind thank you for your time

I'm really thankful to you because of your help

Hope you have a good sleep

Kyle Kanos

For >10k rep: physics.stackexchange.com/a/518650/25301 Rob's comment is sadly spot-on

JMac

00:30

@KyleKanos That answer is essentially spam. Google the first sentence. I know it's been posted to Physics SE and deleted many times.

It's like they spend a lot of time reading questions and articles on dark matter all over the internet, and post that as a response everywhere.

Kyle Kanos

@JMac yes, I wonder if it's the same guy each time though. Or if he has some cadre of believers...

JMac

@KyleKanos I'm not even sure either. It's like a terrible physics meme that people would post as a joke... but they are either all serious or very dedicated to the joke.

Kyle Kanos

Don't underestimate the power of Reddit & 4chan users

JMac

That's why I can't rule out a joke.

Aaron Stevens

00:47

@KyleKanos Ugh I just submitted a paper using this answer to motivate my reasoning.

Slereah

09:28

hello

Muhammed Ç. TUFAN

Hi

yuvraj singh

14:24

@KyleKanos, 2d physics simulator, can you check it for me

I heard from a user that u can help so.

ProjectileMotionApp.java
frame.setSize(900, 600);
frame.setVisible(true);

timer = new java.util.Timer();

timer.schedule(new TimerTask() {

@Override
public void run() {

// has moving objects
if(gui.getScene().inFlux()) {
gui.getScene().updateBalls();
gui.getScene().repaint();
}
}
}, 0, DELAY);
}
}

John Rennie

15:27

@yuvrajsingh is that the code from:

2

Q: 2D Physics Simulation (game-like)

My program is meant to simulate 2D physics(hopefully 3D as well in the future), namely classical mechanics and eventually electromagnetism. Currently it simulates projectile motion by firing a cannonball(which is plainly a black ellipse) from an invisible cannon. It simply spawns an ellipse wit...

Kyle Kanos

@yuvrajsingh looks like Java code. Not sure what you want me to say beyond that because that's much too short of a snippet to be useful

aRockStr

15:48

Browsing the physics stack exchange counts as studying, right?

John Rennie

@aRockStr absolutely! :-)

yuvraj singh

@JohnRennie yes

Actually I saw that code on the site, but I am not too sure about that so I posted it here

skillpatrol

18:03

@DavidZ aren't you going to join in on this year's Winter Bash?

Aaron Stevens

@KyleKanos And you don't like Java ;)

Kyle Kanos

@AaronStevens mostly because it's slow

skillpatrol

is chrome the fastest browser?

Aaron Stevens

@KyleKanos How dare you slander the Oracle

The Last Airbender

18:22

@dmckee can I ask you something about reputation?

Aaron Stevens

@TheLastAirbender Don't ask about asking, just ask.

JMac

@AaronStevens Can I ask you about your comment about asking about asking?

The Last Airbender

Today I got a total of 246 reputation on Physics.SE. How is it possible?

skillpatrol

@JMac Can I ask you about your comment about asking about asking about asking?

Aaron Stevens

@JMac No, but may I ask why you want to ask me about my comment about asking about asking?

JMac

18:24

@AaronStevens Why do you ask that?

skillpatrol

don't ask

Aaron Stevens

@JMac Because I determine my self-worth from what people on the internet think about me

@TheLastAirbender Let's see...

@TheLastAirbender physics.stackexchange.com/users/238497/…

JMac

@TheLastAirbender Acceptance points don't count towards the rep cap, and you seem to have 3 answers accepted today, which accounts for the extra (besides the bonus 1, which is common IIRC, can't remember why)

Aaron Stevens

I think the extra 2 might be from someone removing a down vote on a post

The Last Airbender

Thanks!

skillpatrol

18:27

bottom line: they are only imaginary rep points

JMac

@AaronStevens Oh, that makes sense. And they probably see 246 instead of 247 because they've downvoted something and can see that reflected in their points, while AFAIK no one else can see those numbers on in the reputation tab.

Aaron Stevens

@skillpatrol They aren't imaginary. I see them right there.

@JMac Nailed it. Let's make a meta post to celebrate

skillpatrol

Hooray!

JMac

@AaronStevens I'm going to title it 'The Tyranny of Physics Stackexchange" and then the body will just be my theory about super solid quantum protogravity.

skillpatrol

@AaronStevens you can say that about imaginary numbers too :P

Aaron Stevens

18:31

@JMac Ah yes, I heard SSQP is really gaining ground now

JMac

@AaronStevens I would hope so. I have a bot working overtime to spam it as an answer to any question or comment section on any site that mentions "Dark Energy".

Aaron Stevens

@JMac I think that really is the only way to get the word out

JMac

@AaronStevens It seemed a lot easier than learning about the field, doing actual research and publishing something that academics could understand!

Aaron Stevens

@JMac I think that method of doing science is becoming quickly outdated. No one has time to really understand anything these days. The best any one can ever do now is personal theories.

I mean someone has to be right at some point

Isn't that what Einstein did?

All he knew was patents

Kyle Kanos

@skillpatrol depends on the metrics, but i think Opera is, actually

JMac

18:36

@AaronStevens I mean really, no one can truly know what's real anyways, so we're much better off to believe what we feel is right and dismiss everyone else as biased. This makes sense, because they clearly are all biased by their own personal feelings.

skillpatrol

@KyleKanos thanks

Kyle Kanos

but really "fastest" is a bad metric, honestly

Aaron Stevens

@JMac If it feels good, do it

Kyle Kanos

a rocket shuttle is fast, but do i need that to get across the US? obviously not

JMac

@AaronStevens Great, now you just got a song stuck in my head.

Kyle Kanos

18:38

i'd rather my reliable car to get across the US

or maybe a commercial airline

Aaron Stevens

@JMac Which one

Sorry

Kyle Kanos

but either way, using the "fastest" browser may not be what you want, you might actually want the most reliable browser

Aaron Stevens

May I ask you which one?

Kyle Kanos

and, obviously, that'd be a TOR browser

JMac

@AaronStevens en.wikipedia.org/wiki/If_It_Feels_Good_Do_It Got a lot of radio play around here because they are a fairly local band.

skillpatrol

18:40

@KyleKanos thanks for the recommendation

Aaron Stevens

@JMac Ha that's funny..

JMac

@AaronStevens Yeah, the words "If it feels good do it" are the catchy part of the song.

Kyle Kanos

if murder feels good, should you do it?

Aaron Stevens

@KyleKanos If murder doesn't feel good should you not do it?

Kyle Kanos

@AaronStevens correct

0

Q: Using computational physics to calculate acceleration in a pulley system

I am trying to calculate the acceleration of this simple pulley system: Up until now I was able to take into consideration the two weights, the mass of the pulley and the friction between the pulley and the axle. I am however stuck on the rope of the mass. I thought about considering the mass...

newtonian-mechanics forces computational-physics

why is this tagged computational-physics?

Aaron Stevens

18:43

@KyleKanos Uh, did you even read the title?

Kyle Kanos

@AaronStevens that's the next question

why is there a tag in the title

Aaron Stevens

I guess there is no line between "computational physics" and "physics where I used some computations"

JMac

To be fair, he does seem to have the goal of programming and simulating it on the computer. I think it fits fine as computational physics. I wouldn't necessarily say it's a good question for the site; but IMO the tag fits.

Kyle Kanos

18:59

@JMac i don't really think that's his goal, just how he was going to solve the problem b/c he didn't think it would be analytic

JMac

@KyleKanos I consider that his "goal" for the sake of the question still. It seems to be a poor goal based on his misunderstanding; but he did seem to be asking specifically about doing it computationally, because he thought that was what it would take. I think he used the tag right, he just asked the wrong question.

ACuriousMind

19:50

I am still hatless :(

skillpatrol

:(

Kyle Kanos

@ACuriousMind i think i am too

but i'm mostly indifferent about it

Aaron Stevens

Same

JMac

Yeah I'm hatless too. I just let it happen if it's supposed to happen. And Aaron get out of here with your hat.

Aaron Stevens

I thought it was a Bane costume

JMac

19:54

@AaronStevens Any hat is a bane costume if you wear it wrong enough...? Yeah that sounds like a good moral. Lets go with that and pretend it's deep.

Kyle Kanos

i once collected all but like 1 or 2 hats

took way too much work

and gave me nothing (exccept bragging rights over Brandon)

so then i stopped caring

Aaron Stevens

I'll start trying when they roll over to following years

JMac

I'm still trying to figure out how to exchange these fake points for prizes before I try to get any hats.

Aaron Stevens

@JMac Oh you haven't gotten your prize package yet?

Kyle Kanos

seriously? you haven't?

Aaron Stevens

19:57

I would have more rep than @JohnRennie if I didn't keep exchanging my points for prizes

3

JMac

@AaronStevens IDK, last time I tried to redeem the points for a prize package at Walmart they treated me like they didn't know what I was talking about.

Same thing with the grocery store.

Aaron Stevens

@JMac How many times did you wink?

JMac

@AaronStevens I reviewed my video footage, and I winked the 4.5 times that it told me to wink in the manual. Is my manual outdated?

Aaron Stevens

@JMac I think a better question is how you got access to Walmart video security footage

JMac

@AaronStevens My video footage. I have 15 go-pro's on me at all times filming multiple angles so that NASA can't sneak up on me and install more mind control chips.

2

Aaron Stevens

20:01

@JMac How did you get 15 go-pros without using SE points?

JMac

I'm a bit worried that you didn't assume as much.

@AaronStevens Reddit karma.

Aaron Stevens

@JMac Well there you go. Just convert your SE points to Reddit karma

dmckee

Apropos the discussion on reputation above, you can get 1 rep if someone deletes an answer that you had downvoted.

JMac

@dmckee But we wouldn't see that when viewing their profile, right?

dmckee

Just as an alternative to +2 for a un-downvote on one of your posts and -1 for a downvote applied by you.

@JMac No. I don't think you would.

JMac

20:05

@dmckee That's how we sluethed out what we think happened. They must have downvoted 1 question (which is why they saw their own rep as +246) and had one downvote removed (or some similar combination) and that's why we saw +247 and they saw +246.

Aaron Stevens

@JMac I'd give you a sleuthing hat if I could

I think it would be more aligned with the holiday spirit if hats were awarded to users by other users

4

JMac

@AaronStevens It was a team effort. Not the most complicated ARG I've seen; but we nailed it.

John Rennie

My 2020 hat has been taken away! The swine!

Aaron Stevens

@JohnRennie Hats obtained via time travel are not allowed

John Rennie

That takes me down to three hats. A far cry from my heyday.

ACuriousMind

20:22

@AaronStevens The cynical mod sees just another incentive for sockpuppetry there ;P

Aaron Stevens

@ACuriousMind Well that is not aligned with the holiday spirit, so by definition it cannot happen

QED

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