0852: "Local g"

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Invisiblemoose
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Re: 0852: "Local g"

Postby Invisiblemoose » Wed Jan 26, 2011 8:24 am UTC

Another glaring error (with "misson" still in recent memory), awkward writing even by Randall's standards (especially the angry shouts from the athletes), and clumsy execution...

The comic would have been much better (and more XKCD-like) if there was no text in the last panel...

killminusnine
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Re: 0852: "Local g"

Postby killminusnine » Wed Jan 26, 2011 8:28 am UTC

"Come now, do you really expect me to perform typo correction while an angry mob of pole vaulters are breaking in through my balcony?"*

http://xkcd.com/123/

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shashwat986
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Re: 0852: "Local g"

Postby shashwat986 » Wed Jan 26, 2011 9:04 am UTC

The first time I read the comic, it was AWESOME....
Then I made the mistake of reading the forum. So, now the @$#%ed typo is all I see...
Apparently, 1 in 5 people in the world are Chinese. And there are 5 people in my family, so it must be one of them. It's either my mum or my dad. Or my older brother Colin. Or my younger brother Ho-Chan-Chu. But I think it's Colin -- Tim Vine

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Midnight
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Re: 0852: "Local g"

Postby Midnight » Wed Jan 26, 2011 9:19 am UTC

Hey, everyone! Pole vaulters can pole vault!

seriously, c'mon. It was a solid setup, and at the VERY LEAST make a joke about how they were in a particular city, and THAT'S how they broke in.
As so:
Panel x: "What about the balcony? They're pole vaulters, after all" / "Nah, it's too high, even for them." / "but... we're in Rio De Janiero"
panel x+1: <stare at each other>
panel x+1: <stare at each other> / <"crash" off-screen> / "crap."

Cause that was too many panels for "pole vaulters can break in on the second floor, hurr"


Alternatively, but unlikely: The "buy" typo is in fact the punchline of the comic, because his fans will get so angry that a guy spelled a word wrong once. Which IS amusing.
uhhhh fuck.

kári
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Re: 0852: "Local g"

Postby kári » Wed Jan 26, 2011 9:29 am UTC

Am I the only one who, after seeing the typo, looked for other typos and stared like five minutes at the 'affect' in the next pane?

Dave
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Re: 0852: "Local g"

Postby Dave » Wed Jan 26, 2011 9:42 am UTC

A_of_s_t wrote:O no, here we go.

Inb4 this whole thread is about the typo.



Too late.

I also saw the typo. It's no big deal.

munster tom
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Re: 0852: "Local g"

Postby munster tom » Wed Jan 26, 2011 9:46 am UTC

I was more concerned about the title Local G - which would mean a totally different set of calculations with universal constants changing (again).

Great comic :)

I think the last four panels add a second layer of humour with the slow realisation of the idiocy and added facepalm ... and who hasn't made those style comments at least once ...

TK

gbella
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Re: 0852: "Local g"

Postby gbella » Wed Jan 26, 2011 9:58 am UTC

"Local g"
"Pole"
"Difference of 2cm"

My girlfriend immediately noticed a hidden message there...

jayarava
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Re: 0852: "Local g"

Postby jayarava » Wed Jan 26, 2011 10:08 am UTC

The world record for pole-vault has typically advanced by 1cm intervals since the 1980s. Though the current men's record was set in 1994 @ 6.14m. 0.25% of 6m is 1.5cm!

purpleriot
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Re: 0852: "Local g"

Postby purpleriot » Wed Jan 26, 2011 10:24 am UTC

At first thought the typo might be part of the joke. But then it wasn't. Oh well.

SparkOut
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Re: 0852: "Local g"

Postby SparkOut » Wed Jan 26, 2011 10:31 am UTC

I immediately noticed the "buy" typo too, but I came here wondering whether the thread here would be about the comic or whether it would have reawakened a discussion about the validity of the term "centrifugal". I got a sneaky feeling that's what Randall intended, or at least reinforce that message.

Lo'oris
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Re: 0852: "Local g"

Postby Lo'oris » Wed Jan 26, 2011 10:42 am UTC

space_raptor wrote:I gotta say, the comic could have done without the very last panel. Kinda ruins the joke.

I agree, it is... just unfun. A soulless poor non-joke.

bedges
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Re: 0852: "Local g"

Postby bedges » Wed Jan 26, 2011 10:45 am UTC

On my way to work this morning I passed a man carrying a long thing on his shoulder. I asked him "Are you a pole vaulter?"

He stopped and replied "Actually I'm German - how did you know my name was Walter?"




All punctuational, grammatical and typographical issues present (or not) in this post are, like spacetime, relative. They were doing just fine until you observed them.

Pazuzu
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Re: 0852: "Local g"

Postby Pazuzu » Wed Jan 26, 2011 10:50 am UTC

killminusnine wrote:"Come now, do you really expect me to perform typo correction while an angry mob of pole vaulters are breaking in through my balcony?"*

http://xkcd.com/123/

"No, Randall. I expect you to eat pie."

Amomynous
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Re: 0852: "Local g"

Postby Amomynous » Wed Jan 26, 2011 11:18 am UTC

English is a crazy rule, and everything has exceptions. This is one of those times. Yes, it starts with 'How', but it's still a statement, and statements deserve periods(Or exclamation marks). I tried finding a proper source for myself, but I couldn't find anything more than random conjecture on the internet. While I'm good at rules of English, I'm not good at explaining them.

As a good telling example, though, try this: say the sentence out loud as a question. See if it even sounds right. It won't, because it's not a question :p.
[/quote]

You could always just refer to it as a Rhetorical Question, seeing as that's what it is anyway =P

The question mark is pointing out that that you're asking something, that you want an answer. 'Questions' like "Well that was obvious, wasn't it." don't require an answer, therefore don't require a question mark.


Also, i am the worst Grammer Nazi i've ever come across. I can't have a conversation with somebody that doesn't spell correctly or write in proper English, so this really kicked me in the balls.

LordBritish
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Re: 0852: "Local g"

Postby LordBritish » Wed Jan 26, 2011 11:35 am UTC

dspeyer wrote:What about the increased distance from the center of the earth by centrifugal bulging? Shouldn't that cancel it out?

(Ignoring mountains)


No, the non-spherical shape of the earth even increases the difference:

we have three factors:
* The rotation radius (shortest distance to rotation axis) is much smaller the more you go towards the poles. In Poland At the poles it is zero.
* Due to earth being flattened along the axis from pole to pole, there is an additional radius difference affecting the centrifugal force
* Gravity is lower if there is a larger distance to the gravity center.

Let's look for example at Quito, Equador and Oulu, Finland.

Effect 1:
Earth radius = 6378100
Quito: Rotation radius at latitude 0 = r cos 0 = r 100% = 6378100
Oulu: Rotation radius at latitude 65 = r cos 65° = r 42% = 6378100 * 0,423

Rotation angular frequency of w = 2 Pi/86400 = 7,27E-5.

Zentrifugal forces:
Quito: w^2 * Er = 0,033731 m/s^2
Oulu: w^2 * Er * cos 65° = 0,014255 m/s^2

relativ to g this is a difference of 0.2%


Now adding the effect of the oblate spheroid:
Earth polar radius = 6356800 m
Earth equatorial radius = 6378100 m

Linearly interpolating 2/3 to Oulo: Er_oulo = 6371000 m
Adding height for Quito (Oulu is at sea level): Er_quito = 6380900 m

Zentrifugal forces revisited:
Quito: w^2 * Er_quito = 0,0337 m/s^2 = 0,033745
Oulu: w^2 * Er_oulu * cos 65° = 0,014239 m/s^2

difference is now slightly larger in favor for Quito, but still 0.2% of g


Gravitational effect:

Quito: g_Gquito = G*m_E/Er_quito^2 = 9,7914 m/s^2
Oulu: g_Goulo = G*m_E/Er_oulu^2 = 9,8219 m/s^2


In total:

g_quito = 9,7914 - 0,033745 = 9,7577 m/s^2
g_oulu = 9,8219 - 0,014239 = 9,8076 m/s^2

a difference of 0.5 %

Edit: typos (what else)
Last edited by LordBritish on Wed Jan 26, 2011 10:05 pm UTC, edited 1 time in total.
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Qeu
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Re: 0852: "Local g"

Postby Qeu » Wed Jan 26, 2011 11:41 am UTC

Actually, I have to call this "Worst research for an XKCD comic ever".

Both men and women pole vault world records stand far away from the next competitor.

There is an 8 cm gap between outdoor non-Altitude Bubka's top mark (6.13m) and the best of Tarasov's marks (6.05m). Bubka's outdoors top mark is at 6.14m on altitude (Sestrière, IT)

Bubka owns the top 13 outdoor marks.

On indoor, there is a 9 cm gap between Bubka's WR (6.15m) and Steven Hooker's top which stands at 6.06m

Bubka owns the top 7 indoor marks.


On women, there is a 14 cm gap between outdoor Elena Isinbayeba WR (5.06m) and the best of Jennifer Suhr marks (4.92m).

Isinbayeba owns the top 11 outdoor marks.

On indoor, there is a 15 cm gap between Isinbayeva's top mark (5.00m) and Feofanovas's top one which stands at 4.85m

Isinbayeva owns the top 10 indoor marks.

se336906
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Re: 0852: "Local g"

Postby se336906 » Wed Jan 26, 2011 12:16 pm UTC

Granted, we are a nitpicky fanbase, but it comes with the territory- Randall's humor often comes from being nitpicky about science, grammar, math, and programming. The typo kills me, but I also think it's hilarious that it's in the same sentence as the word 'centrifugal' which he makes a POINT with the asterisk about spelling correctly (most people incorrectly think it's 'centripetal'), and then he goes and uses the wrong homophone for a tiny word like 'by'. Haa, made me smile.

Smo
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Re: 0852: "Local g"

Postby Smo » Wed Jan 26, 2011 12:19 pm UTC

Rhetorical questions need question marks too because a question mark has a grammatical function which it almost always abides by, BUT in the case of 'How dare you', it's become used so much as an exclamation rather than a question, I think it's down to personal style choice. One thing it isn't is a a statement, however - saying 'how dare you cast doubt on our honour?' is not a statement no matter which way you look at it.

I loved the comic, the last frame was unnecessary but didn't ruin it for me and the typo, while incorrect, was either Randall trolling or it was a simple human mistake.

squig
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Re: 0852: "Local g"

Postby squig » Wed Jan 26, 2011 12:33 pm UTC

Amomynous wrote:Also, i am the worst Grammer Nazi i've ever come across. I can't have a conversation with somebody that doesn't spell correctly or write in proper English, so this really kicked me in the balls.

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Faithful
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Re: 0852: "Local g"

Postby Faithful » Wed Jan 26, 2011 12:40 pm UTC

I found this funny.

That is all.

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sorceror
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Re: 0852: "Local g"

Postby sorceror » Wed Jan 26, 2011 1:03 pm UTC

Just thought about this two days ago, in the context of weightlifting. So, get out of my... quit standing on the doorstep of my head, Randall!

cogitoergocogito
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Re: 0852: "Local g"

Postby cogitoergocogito » Wed Jan 26, 2011 1:14 pm UTC

Ummm... I don't see the typo. What I currently read, as of 7:10 A.M. Central time, is that it actually says "by." Is there some weird grammar rule between the two that I am not getting (making "by" the wrong choice), did Randall fix it, or am I (or all of you, as I suspected earlier) going crazy?

By the way, it sounds like someone had problems with jocks in his day.

RD Padouk
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Re: 0852: "Local g"

Postby RD Padouk » Wed Jan 26, 2011 1:23 pm UTC

When I was in school the mark of one educated in physics was to constantly remind people that centrifugal force wasn't a real force; It was just a perceived force resulting from a non-inertial frame of reference. And this is still true, of course, so I was originally confused by this comic. Then I realized that Randall is referring to the reactive force given by (M V^2)/R caused by the earth's rotation. I had never heard this referred to as a "centrifugal force" before. Instead, I've always just seen this term as a part of the equations for escape velocity. That is, an object at a higher altitude is moving a tad faster than one at a lower altitude, and hence less energy is needed to escape the earth's gravity well. In this formulation pole jumpers at a higher elevation have an extra boost caused be the rotation of the earth, so they have to exert less energy to get to a given height above the ground- and the same goes for rockets. So this was a new and interesting way of looking at it for me. And, of course, the comic was funny as hell.

Netzach
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Re: 0852: "Local g"

Postby Netzach » Wed Jan 26, 2011 1:28 pm UTC

Oh, he DID rewrite it. The "by" in the first panel used to be "buy".

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Dauthi
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Re: 0852: "Local g"

Postby Dauthi » Wed Jan 26, 2011 1:32 pm UTC

Regarding the question mark controversy... There is a demand for an answer; therefore, it is a question. It may be rhetorical, i.e., the asker may not actually expect an answer, but it is still asking for one. And how do you know that the asker wasn't genuinely seeking a response? (Was that question rhetorical or genuine? What about that one? This one? At least one of those was rhetorical, should I have used question marks?)

Just because that particular phrase has been overused [by people (i.e., Hollywood) who probably don't even understand what they're asking (they are more likely just repeating an oft-heard phrase of self-righteous indignation)] does not mean that the inherent question becomes meaningless or invalid.

What about if it was "how could you question my honor?"? Would the juxtaposition of one word really make one a declarative sentence and one an interrogative? English is certainly a strange language, but that seems a little extreme even for it. The answers to both would yield pretty much the same results.

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Almost in register
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Re: 0852: "Local g"

Postby Almost in register » Wed Jan 26, 2011 1:37 pm UTC

Please stop calling it a typo; it's not a typo if you don't type anything.

Also, the error looks to be fixed.

Dauthi wrote:Regarding the question mark controversy... There is a demand for an answer; therefore, it is a question.

Sorry, no. Try reading it as a bona-fide question. The emphasis ends up in the wrong spot (either on "doubt" or "honor"). For it to have the correct emphasis (on "dare"), it needs to be an exclamation.

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Re: 0852: "Local g"

Postby Hungry_Myst » Wed Jan 26, 2011 1:40 pm UTC

Damn guys, it's a typo, get over it.

Turns out the author is human and makes human mistakes, go figure.

DutchUncle
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Re: 0852: "Local g"

Postby DutchUncle » Wed Jan 26, 2011 1:40 pm UTC

While fearing the possible impact of rampant commercialism on XKCD, I hope you submit this to Sports Illustrated.

PS - people who complain about typos should check their apostrophes ("its" vs. "it's"). Just sayin'.

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Re: 0852: "Local g"

Postby eviloatmeal » Wed Jan 26, 2011 1:53 pm UTC

Let me see if I understand this.

Being further from the center of the earth means there is a stronger push "upward" due to the rotation of the earth around itself? Then wouldn't pole vaulting at night be much more efficient due to rotation around the sun?
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spencerogden
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Re: 0852: "Local g"

Postby spencerogden » Wed Jan 26, 2011 2:02 pm UTC

This has actually come up in sports. In the America's Cup, the boats have very strict weight tolerances to ensure that they are within the rules. Last time around, they had event both on the Med and in Malmo. When they went to Malmo, the weight difference was enough for the scales to detect, and the calibration procedures had to be amended to account for this effect.

Jopster
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Re: 0852: "Local g"

Postby Jopster » Wed Jan 26, 2011 2:19 pm UTC

eviloatmeal wrote:Let me see if I understand this.

Being further from the center of the earth means there is a stronger push "upward" due to the rotation of the earth around itself? Then wouldn't pole vaulting at night be much more efficient due to rotation around the sun?

The push upward is really the earth slinging you around. This happens to be at the places where you are further from the sun.
Well, actually you are further from the center because the ground itself is being slinged away.


I have another question though:
Has it been taken into account that with lower gravity you can also accelerate less horizontally? This is at least the case for regular walking; I think the maximum speed of walking is linearly dependant of the gravitational acceleration.
I could imagine this being the case for running as well, and if so, this might make the difference in maximum height even smaller.

Jacob Luke
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Re: 0852: "Local g"

Postby Jacob Luke » Wed Jan 26, 2011 2:36 pm UTC

Uh guys...

Between the now irrelevant Grammar-Nazism and the claims of this being the worst-researched XKCD ever because Randall isn't an expert on the [Sarcasm] wonderfully exciting, eternally-central-to-the-world-stage [/Sarcasm] sport of pole-vaulting, this thread is somewhat pathetic. Really, I'm disappointed there's so little discussion on the actual science of this strip and so much on the little unimportant nitpicks.

I only posted because I noticed elsewhere some reference to the (extremely minor and perfectly human) error, but couldn't actually find it because Randall corrected it because you all complained so much. Geez, guys/girls/spambots...

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Re: 0852: "Local g"

Postby Posthumane » Wed Jan 26, 2011 2:59 pm UTC

I've never thought about the differences in gravity affecting Olympic sports, but one thing that HAS bothered me is the way they do starts for a sprint. They have a guy on one side of the track who fires a starting pistol, and I assume that's when the timing starts. However, being that the track has some width to it, the racer farther from the starting pistol will hear the sound a fraction of a second later than the guy closest to it. The time differences between racers are often incredibly small, so it might make a difference. If the track is 30m wide, the difference would be about 0.1 seconds, right?

Also, location makes a big difference in terms of world records. Speed skating is a good example - Calgary is known to have the fastest speed skating ice anywhere, so if you try to beat the world record for track times you would have a much harder time doing it anywhere else.

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Osprei
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Re: 0852: "Local g"

Postby Osprei » Wed Jan 26, 2011 3:03 pm UTC

Being further from the center of the earth means there is a stronger push "upward" due to the rotation of the earth around itself? Then wouldn't pole vaulting at night be much more efficient due to rotation around the sun?


Actually, wouldn't it be better during the day, since the sun would be pulling you higher? During a solar eclipse at noon on the equator would then be best.

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Phrozt
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Re: 0852: "Local g"

Postby Phrozt » Wed Jan 26, 2011 3:17 pm UTC

Is the math right on this one?

I'm not questioning the .5% of a difference... but rather the values he's saying. Saying a 5m vault could be 2cm off is as if he's saying that .5% of the jump happened in 0g. I could be wrong.. but it doesn't sound right..

winklerd
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Re: 0852: "Local g"

Postby winklerd » Wed Jan 26, 2011 3:21 pm UTC

Jesus Christ people, do you never make a mistake at your job? There's a difference between making a spelling or grammatical mistake because you're too stupid to know better and making a simple typo.

"Oh me yarm, my eyes are bleeding, fix it now plz."
"I can't believe Randall would make such an error!"

Grow up.

Jonathan SCE
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Re: 0852: "Local g"

Postby Jonathan SCE » Wed Jan 26, 2011 3:30 pm UTC

Posthumane wrote:I've never thought about the differences in gravity affecting Olympic sports, but one thing that HAS bothered me is the way they do starts for a sprint. They have a guy on one side of the track who fires a starting pistol, and I assume that's when the timing starts. However, being that the track has some width to it, the racer farther from the starting pistol will hear the sound a fraction of a second later than the guy closest to it. The time differences between racers are often incredibly small, so it might make a difference. If the track is 30m wide, the difference would be about 0.1 seconds, right?


This is why most starting blocks have a speaker built into them so all the athletes hear the gun at the same time.

http://en.wikipedia.org/wiki/Starting_blocks

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space_raptor
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Re: 0852: "Local g"

Postby space_raptor » Wed Jan 26, 2011 3:42 pm UTC

Supershadow18 wrote:
cjdrum wrote:How dare you state that a period is meant to come at the end of a sentence starting with "(H)ow"? No pun intended.

It's basically, "How can you dare to...". So it needs a question mark.

Sorry. This guy is exactly me.


English is a crazy rule, and everything has exceptions. This is one of those times. Yes, it starts with 'How', but it's still a statement, and statements deserve periods(Or exclamation marks). I tried finding a proper source for myself, but I couldn't find anything more than random conjecture on the internet. While I'm good at rules of English, I'm not good at explaining them.

As a good telling example, though, try this: say the sentence out loud as a question. See if it even sounds right. It won't, because it's not a question :p.


I don't think so. It sounds like bad anime if you don't read it as a question.
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J.D. KaPow
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Re: 0852: "Local g"

Postby J.D. KaPow » Wed Jan 26, 2011 3:44 pm UTC

Amomynous wrote:Also, i am the worst Grammer Nazi i've ever come across. I can't have a conversation with somebody that doesn't spell correctly or write in proper English, so this really kicked me in the balls.


This statement is far more amusing than anything in today's comic. And I quite enjoyed the comic.


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