# 852: Local g

(Redirected from 852)
 Local g Title text: In Rio de Janeiro in 2016, the same jump will get an athlete 0.25% higher (>1cm) than in London four years prior.

## Explanation

Cueball explains in the first panel, that the centrifugal force (not be confused with the centripetal force - which is made clear in 123: Centrifugal Force - cited in the first frame of this comic) along with variations in the earth's shape causes the gravitational force to vary by half a percent between some cities. These variations could have a significant effect on certain sporting events; for example, Cueball explains that a pole vaulter might jump 2 cm higher in a city with a smaller gravitational force.

So Cueball writes an article reevaluating pole vaulting world records based on the city in which the record was accomplished. His article suggests that some athletes should not have received an award for breaking a record because they did so in a city with a below average gravitational force. These pole vaulters whose records were questioned by Cueball's article angrily stage a protest outside of Cueball's apartment.

Then Cueball proceeds to taunt them reasoning that they can't harm him because his building is locked. Cueball and Megan then hear a crash indicating that the protesters have managed to reach the apartment's balcony. When Cueball asks out loud how the pole vaulters reached the balcony, Megan stares at him for a moment and then he realizes the stupidity of that question: the pole vaulters pole-vaulted onto the balcony.

At the title text Randall explains that in fact the gravity force at the Olympic Games at Rio de Janeiro in 2016 compared to London in 2012 will make a difference of more than one centimeter, mainly because Rio de Janeiro is much closer to equator than London resulting in an increased centrifugal, or, perhaps centripetal, if you prefer to be more contrasting, force.

## Transcript

Cueball: Did you know that because of centrifugal* force and the shape of the Earth, "gravity" can vary by nearly half a percent between major cities?
*Yes, centrifugal. xkcd.com/123
Cueball: That's not a lot, but it could affect, say, pole vaulting. In a 5m jump, it could make a difference of 2cm.
Megan: Huh, interesting.
Cueball: I'm going to write an article reevaluating vaulting records to take this into account.
Three days later:
Megan: Good job. There's an angry mob of athletes outside.
[He looks off the balcony. The mob of athletes is out of frame.]
Athlete: That record was mine!
Athlete: How dare you cast doubt on our honor?
Athlete: Have you no respect?!
Athlete: Make him pay!
Cueball: Hey, the math doesn't lie. Suck it, jocks.
Megan: Dude, don't provoke them.
Cueball: Whatever. The building's locked. Let 'em vent for a-
crash
Off-panel Athlete: GET HIM!
Cueball: Crap!
Cueball: How did the pole vaulters get up to our balcony?
Megan: ...
[Beat frame.]
Megan: That might be the stupidest question I've ever heard.
Cueball: Right.

# Discussion

What a coincidence that he just happened to p*** off the one group of athletes that was capable of reaching and meting out retribution on him. Davidy²²[talk] 07:12, 17 April 2013 (UTC)

This explanation is lacking. It does not talk about the joke itself. It is talking about the variation in gravity being significant in interpreting world records. 184.66.160.91 05:14, 8 July 2013 (UTC)

Hi 184.66.160.91, don't criticise but help to explain. Nevertheless I will start to work on this right now.--Dgbrt (talk) 20:16, 8 July 2013 (UTC)
Criticising is helping. 184.66.160.91 06:18, 17 July 2013 (UTC)
While constructive criticism is helpful, anyone can edit. If you see problems in the article, click "Edit" and make the improvements yourself. That's what Dgbrt meant by "help to explain". (And yes, I do realize this conversation is a few months old.) NealCruco (talk) 22:43, 22 November 2013 (UTC)
No, no it's not. Criticizing without offering even a partial solution, is just adding noise to the signal. I don't even believe that stating things without an alternative in mind is criticizing. It's just trolling. Cflare (talk) 15:10, 13 August 2014 (UTC)

Well,it doesn't just affect pole vaulters, it affect all sports, like running, less graity makes you run faster. Or maybe slower? ~Jfreund

The added traction is definitely offset by the increase in force required to maintain height off the ground. So maybe you'd start faster, but you'd definitely end slower. This is why records are a questionable metric. Not only do small things like this completely affect the results, but shifts in these things over time. As well as increases in biotechnology, training, and genetic offerings. It's weird how this has nothing to do with survival on the grand scale, yet we see humans adapt over time like this. Either we are generically becoming better on every metric, or willpower has an effect on offspring. It's possible that athletes find athletes and have kids. I don't know; it is a mystery. Cflare (talk) 15:14, 13 August 2014 (UTC)
I believe being a winner in sport - especially men - will increase his change for mating and (therefore) procreation. Arifsaha (talk) 19:33, 8 October 2014 (UTC)
This isn't evolutionary; to establish evolution you need to show that a trait is inherited and those with the trait have produced more offspring over time. Marginal changes in general health and fitness are impacted by diet and related to relative poverty - I find it difficult to believe there is a selective signal in something that is overwhelmingly skewed by environment/context. Most likely, general wellbeing has increased due to greater access to education, welfare, etc. I bet if you look at economic crashes like Russia post 1991 and the western world post 2008, you'd find decreases in these abilities following soon afterward. 108.162.250.158 23:33, 20 March 2016 (UTC)

Is nobody going to mention the spelling mistake in the first panel? "Buy" instead of "by" ~Jack 141.101.98.93 (talk) (please sign your comments with ~~~~)

It affects more than sports. I work in calibration. A weight used for *force* measurements (10N, for example) has to be calibrated for local gravity - 1% change in local gravity vs 0.1% weight tolerance...108.162.219.154 15:39, 19 May 2017 (UTC)

The explanation usually given for Bob Beamon's 8.91 metre (29.75 ft) long jump at the 1968 Olympics is that the Mexico City air (at an altitude of 8000ft/2480m) was thinner. But sure, if you also want to credit as well something that needs special, high-calibration equipment and complex math to measure, go ahead. ####