3136: Pull

Explain xkcd: It's 'cause you're dumb.
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Pull
Be careful fighting gravity. If you win, it's a long way down.
Title text: Be careful fighting gravity. If you win, it's a long way down.

Explanation

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Megan and Cueball are lying in the grass on an orb, presumably Earth. However, instead of the conventional frame orientation where gravity points towards the bottom of the image, the viewpoint is stationary outside the Earth while we see it slowly rotating. Shown this way, we feel an intuition that the protagonists should fall off and it makes it clear how weird it is that gravity keeps us stuck to an orb.

In the first panel, Cueball expresses that he doesn't like being stuck there, possibly because he wants to explore other worlds or because he finds Earth limiting. The alternative would be "falling off", as in the reader's viewpoint where he might slide and fall towards the bottom of the frame. However in reality if gravity would suddenly be switched off on Earth, apart from catastrophic effects on the planet and the atmosphere, he would initially just float with the Earth, not "fall" anywhere.

Transcript

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Cueball: I don't like being stuck to this orb,
Cueball: but I guess falling off would be worse.
Megan: I wouldn't mind if it pulled a little less hard, though.
Megan: I have places to be.
Megan: I shouldn't just lie around in the grass.
Cueball: Maybe the pull will weaken if you wait around a little longer.
Megan: Good idea. I'll give it another five minutes.

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Discussion

Australia reference????? /s TheTrainsKid (talk) 05:41, 2 September 2025 (UTC)

I recently learned that earth has weird gravity effects caused by a big moon orbiting near the surface. These are probably also barely measurable, except e.g., big bodies of water --134.102.219.31 11:23, 2 September 2025 (UTC)

I take it you haven't heard of Earth tides? [1] --Gorcq (talk) 11:54, 2 September 2025 (UTC)
Perhaps you should follow the link in the comment you replied to... Yorkshire Pudding (talk) 13:00, 2 September 2025 (UTC)
It's a real effect. It has been proven by neutron interferometry. (https://en.wikipedia.org/wiki/Neutron_interferometer) -- Lordpishky (talk) 02:30, 3 September 2025 (please sign your comments with ~~~~)
Ya the hemispheres are kinda crazy《プロキシ》(XKCD中毒者) 13:07, 2 September 2025 (UTC)

So I'm not qualified to critique this, but, I think the comic is referencing an unsolved problem - is gravity constant over time? I'm not a physicist and I'm not conversant with the literature, but I think there is some debate on the matter. The line 'give it another five minutes' definitely seems like a humorous reference to the idea that the gravitational constant might change over age-of-the-universe timescales. Hence I suspect the description talking about earth's attraction specifically misses the point. --DW 2607:FB90:8FA9:E54A:5856:AACD:B913:6DD8 13:44, 2 September 2025 (UTC)

Judging from the amount of rotation, the conversation takes place over a period of several hours. -2603:8080:2AF0:F1E0:39BF:23FC:411E:363B 18:58, 2 September 2025 (UTC)

Someting seams wrong with the number in the statement "The net effect of these is for Earth to lose about 520 tons in the 5-minute period". I found that "Each day, around 90 tonnes of hydrogen and helium escape from Earth in the direction of space" https://www.snf.ch/en/2QLt6mvuU4hZj1yx/news/leaking-atmospheres-seal-the-fate-of-planets Maofgf (talk) 19:10, 2 September 2025 (UTC)

It should be "centripetal", not "centrifugal". Inquirer (talk) 20:40, 2 September 2025 (UTC)

Centrifugal force is correct here. Centripetal force is the force keeping an object on a circular trajectory (in a fixed reference frame), in this case it is gravity. In the rotating reference frame, the object is stationary, as centripetal and centrifugal force cancel each other out. As soon as gravity stops, there is no centripetal force anymore. In the rotating reference frame, the object accelerates outwards by the centrifugal force (on a curve due to the Coriolis force); on an fixed reference frame, there is no force and it travels in a straight line. 2A02:1210:82E7:3100:37D6:4369:7925:6854 22:01, 2 September 2025 (UTC)

I'm completely failing to understand the stuff about "roughly three more minutes until they "fell" off-panel". What's that based on? BunsenH (talk) 20:57, 2 September 2025 (UTC)

This is disturbingMathmaster (talk) 21:58, 2 September 2025 (UTC)

Is the centrifugal effect at the equator truly exactly 0.34% of the gravitational acceleration at the equator? That seems like an astonishing mathematical coincidence, to be a ratio that is an integer over a small power of ten! 47.150.86.14 05:45, 3 September 2025 (UTC)

It's not exact; I've removed that phrase. BunsenH (talk) 14:33, 3 September 2025 (UTC)

Proof Earth is a Katamari. VonAether (talk) 13:47, 3 September 2025 (UTC)

It's a long way down only if you don't have a method of self-propulsion, like Superman!2600:100F:B1BF:AAD5:F118:400C:2C92:2C67 12:43, 14 September 2025 (UTC)
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