explain xkcd - User contributions [en]

2983: Monocaster

2024-09-16T11:22:00Z

172.69.194.143: /* Explanation */

{{comic
| number = 2983
| date = September 9, 2024
| title = Monocaster
| image = monocaster_2x.png
| imagesize = 536x673px
| noexpand = true
| titletext = My competitors say the tiny single tiny caster is unsafe, unstable, and offers no advantages over traditional designs, to which I say: wow, why are you guys so mean? I thought we were friends!
}}

==Explanation==
{{incomplete|Created by a LAPTOP-CONTROLLED HAMSTER BALL - Please change this comment when editing this page. Do NOT delete this tag too soon.}}
A caster, also spelled castor, is a small unpowered wheel, usually attached to a swiveling base. They are typically found on carts and office chairs to make them easy to move, and may be placed on heavy appliances to facilitate movement.

Randall has proposed a variant of the skateboard with only one caster on the bottom, the titular "monocaster", and devoted most of the comic to a {{w|Perceptual mapping|perceptual map}} showing the variety of wheeled vehicles. Market strategists and investors use such diagrams as a simple way of representing important differences between products or companies, but where a consumer might be more concerned with features like speed, cost, ease of use, or carrying capacity, this map focuses on the number of wheels (horizontal axis) and the diameter of those wheels (vertical axis).

Each axis uses a logarithmic scale, which is convenient for making the map look more evenly filled but also visually exaggerates the size of the "key gap" that the monocaster is filling, which can be described as "vehicle with a single wheel smaller than 25 cm". The nearest competitors appear to be a two-wheel skateboard sometimes called a {{w|caster board}} (wheel diameter under 8 cm) and a single-wheel self-balancing board resembling a {{w|Onewheel}} (diameter around 25 cm). The Onewheel is sometimes described as a {{w|monowheel}} (though these are traditionally larger like the "1920s monowheel" on the upper left). Randall appears to have combined these two names to create the monocaster. This gives up several of the competitors' features - the caster board's two wheels provide enough stability to propel the vehicle manually, while the Onewheel's single wheel is wide (assisting with sideways balance) and powered by a self-balancing mechanism.

The result resembles a {{w|Balance board#Sphere-and-ring|"Sphere-and-ring" balance board}}, or other types, though these provide limited locomotion potential. The joke depends on the caster's obvious impracticality in this role: the hole in the market was open ''for a reason''. The obvious drawback to any single-wheeled vehicle is that it's difficult to balance: the rider has to avoid falling forward or backward, as well as to either side. This is a major reason why one-wheeled vehicles are uncommon to begin with, but those vehicles which do exist compensate by using relatively large wheels, driven either by human power or a motor, which creates rotational inertia and allows the rider to balance simply by leaning forward.

A single, small, undriven wheel eliminates these balancing forces, meaning that the user would essentially need to balance on a single point. Also, most casters swivel, meaning that the balance point would move around under the rider's feet and make it even more difficult to balance. In addition, there's no apparent means of propulsion, which means the only way to move forward would be to either roll exclusively downhill, or use one foot to push off the ground. Either strategy would make retaining balance almost impossible.

Multiple-wheeled vehicles greatly reduce the issue of balance simply by having multiple points of contact with the ground. The size of the wheels varies greatly; small, rigid wheels are generally suitable only for flat, smooth, rigid surfaces at relatively slow speeds, while vehicles expected to handle high speeds and varying road (and off-road) conditions will necessarily have larger wheels.

The "monocaster" design offers no advantages and would be nearly unrideable, making it obvious why such a vehicle has never been seriously proposed.

The title text extends the joke by listing the disadvantages mentioned above, but not providing a rebuttal. Instead it only attempts an emotional appeal by saying that the competitors are being mean and by commenting that Randall believed they were friends.

{| class=wikitable
! scope="col" | Vehicle
! scope=“col” | Number of wheels
! scope=“col” | Wheel Diameter
! scope="col" | Explanation
|-
| 1920s Monowheel || 1 || 3 meters || A monowheel is a vehicle in which the rider sits inside a single, large, hollow wheel. Versions have existed which were hand- or pedal-cranked, but the "1920s" version portrayed here is apparently motor-driven. These vehicles have generally been seen as novelties, as their stability and practicality issues limit their usefulness for actual transport.
|-
| Unicycle || 1 || 45 centimeters || Probably the best known single-wheeled form of transport, a unicycle consists of a single wheel, usually driven directly by pedals, with a seat mounted on top. Due to their difficulty, they are most commonly used as novelties and for comic performances, more than as practical transport.
|-
| OneWheel || 1 || 20 centimeters || A one-wheeled electric skateboard in which the user stands on both sides of a large, central wheel. The design self-balances by increasing the velocity as the user leans forward. This allows balancing and speed control to operate in a single motion.
|-
| Bicycle || 2 || 45 centimeters || A two-wheeled, pedal-driven vehicle. The relatively simple, inexpensive and efficient design of these vehicles makes them practical for transport in a variety of situations. As a result, they've long been among the most popular and widely-produced vehicles in the world.
|-
| Scooter || 2 || 8 centimeters (*) || A two-wheeled vehicle driven either by pushing with a foot or by an electric motor or fuel-powered engine. Scooters are ridden both for recreation and as a form of transportation in cities.
|-
| {{w|Roller shoe}} || 2 || 1 centimeter (*) || Shoes with small wheels built into the back end of the soles, putting them underneath the wearer's heels (which is what the brand-name "{{w|Heelys}}" is derived from). They allow the user access to wheeled movement by pushing off the ground and balancing on the slightly protuding wheels. This is not as fast or comfortable as a dedicated wheeled vehicle, their rolling action is limited to sufficiently flat surfaces and they are not as easy as regular shoes to simply walk in. But such shoes allow for some degree of both walking ''and'' rolling without having to carry a seperate wheeled vehicle, nor necessarily having the baseline difficulty of other 'fuller' versions of wearable skates.
|-
| Tricycle || 3 || 20 centimeters || Appears to be a {{w|Big Wheel (tricycle)|"Big Wheel" type}} child's toy, which actually have smaller 'trailing wheels', rather than either {{w|Tricycle#Upright|upright}} or {{w|Tricycle#Recumbent|recumbent}} style cycles for adults which ''usually'' match the wheel-sizes of their bicycle equivalents.
|-
| Scooter (three-wheeled) || 3 || 3 centimeters (*) ||
|-
| Monster Truck || 4 || 2.5 meters || Monster trucks are very large vehicles with four large wheels. They are almost always driven as part of events where specifically trained drivers that use them to perform dangerous stunts and crush smaller vehicles. Because of their size, the danger to other vehicle, often very poor mileage, and design choices that can be in violation of local laws and regulations regarding motorized vehicles monster trucks are not driven on public roads and have to be transported in dedicated trailers, making them poor choices for transport where one has to leave private property.
|-
| Car || 4 || 50 centimeters || Cars are motorized vehicles designed to move one or more people and an amount of goods around fast. While almost all cars have four wheels (discounting reserve wheels), there are a few that have more than four (certain limousines) or fewer (the Reliant Robin only has one wheel in the front). Cars are more expensive than most options on the chart due to their higher cost, the use of fuel and maintenance requiring specialized knowledge (and sometimes replacement parts), they make up for this with their speed, access to (at least in most of the world) an extensive system of roads and refueling stations, the ability to move a number of people and goods (how much depends on the exact type of car and how much of either the car is already carrying), and the comfort of being in what is almost always an enclosed and air conditioned compartment. Because of the potential danger of an object of a car's size and speed, drivers are required to perform a test of their ability to both control the vehicle and be aware of other traffic to obtain a license to drive one. Cars are a common source of leisure, with interests ranging from driving them normally, driving them as part of a race, maintaining them or enjoying luxury cars.
|-
| ATV || 4 || 20 centimeters (*) || ATV's or "all-terrain vehicles" are unenclosed, handlebar-steered vehicles designed for off-road riding. They have four, large, low-pressure tires and a robust suspension system to accommodate rough terrain. They generally aren't designed to carry passengers, and have limited cargo capacity, which limits their usefulness for regular transport. They're generally used either for recreation or for transport in areas without well-maintained roads.
|-
| Skateboard || 4 || 2 centimeters (*) ||
|-
| Three-Wheel Skates|| 6 || 4 centimeters (*) || Three-wheeled skates are a type of inline skate (shoes with a line of wheels affixed underneath the shoe) that differ from the more commonly used four wheeled inline skates by having three larger wheels. They are inexpensive and easy to maintain, but they require significant skill to use effectively and the user is reliant on smooth surfaces to skate around on. Another downside is that the wheels cannot be removed from the shoes, requiring the user to either carry an extra pair or have an extra pair at their destination.
|-
| Roller Skates|| 8 || 2 centimeters (*) || Roller skates are shoes with small wheels underneath them in a rectangular pattern. This makes roller skates much more stable than inline skates, allowing users to stand on them with more ease. Like inline skates they are cheap and low maintenance, but in order to move any significant distance without support they require a skilled user, smooth surfaces and the user needs backup shoes when taking them off (though there exist strap-on roller skates).
|-
| Semi-Trailer Truck (Articulated Lorry) || 10-18 || 1 meter || A semi-trailer truck is a motorized vehicle designed to pull trailers that can be easily decoupled from the truck itself. This allows the truck to switch trailers and move a different cargo without having to unload the trailer. The name in brackets that was used here (articulated lorry) is a name most commonly used in British English (or "artic", for short), with articulation meaning that the truck can swivel at the point where the truck connects to the trailer. This allows for the truck to make much tighter turns than if it were one long vehicle, which is another advantage of this configuration, with typically more stability than with a {{w|Drawbar (haulage)|drawbar}} attachment. Trucks are designed to haul cargo for long distances, with the cargo in question being either too heavy or too large to carry with a smaller hopper, tanker, hard-/soft-sided container or flatbed placed entirely upon a single truck chassis. They are driven either by drivers employed by a transport company, or by self-employed individuals who haul cargo for a living. A specialized license is required to drive one, and because of their size (even without a trailer), trucks have more limitations on where they can drive and park than normal cars. Like cars, trucks are a source of leisure, but because of the higher cost to purchase, maintain and drive them, they are more often enjoyed for their aesthetics rather than actually driving them for leisure. There are events like races for trucks, and trucks can be given elaborate paint jobs to have them stand out.
The number of wheels is for both the {{w|Tractor unit#Axles|truck}} and a {{w|Semi-trailer#Types|trailer}}, which can each differ vastly between vehicle configurations. The truck in the comic has five ''obvious'' axle-sets (thus at least ten actual wheels): a single pair of front wheels, two pairs of trailer-bearing rear wheels and two pairs of wheels on the trailer itself. The drawing of the truck actually spans the axis range of three wheels (unlikely to be true, and the minumum for a tractor-trailer would normally be six) all the way up to 16, so it's not entirely clear which number (≥10) Randall intends this one to portray.
|}

(*) It seems that Randall has made some mistakes in regards to the wheel sizes especially in the centimeter range of the diagram. Most of the vehicles have bigger wheels and the number would suggest hat he meant inches instead of centimeters. Alternatively, he may have mistakenly recorded the wheels' radius instead of its diameter, as intended.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

:[A chart picturing many wheeled vehicles with a caption below the chart window. The vertical axis is labeled "Wheel Diameter", logarithmic from 1cm to 5m. The horizontal axis is labeled "Number of wheels", logarithmic from 1 to 16. From top left to bottom right, there is a person with a cap, seated in a circle, labeled "1920s monowheel", a monster truck with a skull and a lightning bolt on the side, a lorry (truck), a Cueball on a unicycle moving back and forth, a Cueball on a bicycle, a car, a Cueball using a Onewheel, a Cueball on a child's "Big Wheel" tricycle, a Cueball on a quad, a Cueball standing on a scooter, a Cueball standing on a board with one small wheel bellow, circled and labeled with two question marks, a three-wheel scooter, a skater, a Cueball using three-wheel skates, labeled "three-wheel skates", a Cueball crouching and using skates, and a small Cueball using shoes with wheels (Heelys) moving forward.]
:Caption: My new monocaster board fills a key gap in the wheeled vehicle market.

{{comic discussion}}

[[Category:Charts]]
[[Category:Comics featuring Cueball]]
[[Category:Multiple Cueballs]]
[[Category:Characters with hats]]
[[Category:Skateboard]]

Talk:2981: Slingshots

2024-09-05T18:20:22Z

172.69.194.143:

We don't put tables in the transcript, which is supposed to be screen-readable. Tables are not screen-readable. [[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 04:25, 5 September 2024 (UTC)
:I now see the hidden "Tables are bad?" content in the incomplete transcript notice! Cute! [[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 04:33, 5 September 2024 (UTC)
::anybody want to change the transcript? not too confident on how to write it. [[User:42.book.addict|42.book.addict]] ([[User talk:42.book.addict|talk]]) 17:06, 5 September 2024 (UTC)
:::Given it a go. Could add "regular column" and "gravitational column" pre-descriptors to the pair of row elements. Also chose to use the [label]s of [Tick] and [Cross] in place of the 'fancy' characters; could have gone with [Ticked], [Marked with a tick], [Affirmed], etc, but this seemed sensible. Obviously still open for editing.
:::If I'd have started from scratch, I would have used the (previously identical) table-markup version in the Explanation but have put the "Yay/Nay/freetext" explanation in there with it. But that's not to say that it doesn't look fairly ok (if not better?) in the paragraph-by-paragraph treatment as it currently is, with the table there as visual repeat only.
:::YMMV on all aspects of my choice/complicit acceptance, naturally. [[Special:Contributions/172.69.194.143|172.69.194.143]] 18:20, 5 September 2024 (UTC)

We should clarify that it's the American Dennis and not the British one. There are differences, which I learned the hard way :( [[Special:Contributions/172.69.43.184|172.69.43.184]] 06:48, 5 September 2024 (UTC)
:I expanded (and moved to a Trivia section) the interesting facts of this coincidence. (And I didn't add [https://www.plagiarismtoday.com/2010/10/18/the-odd-case-of-dennis-the-menace/ this link there], but maybe it's of "not even Trivia" interest, so you can have it here instead.) [[Special:Contributions/172.70.86.37|172.70.86.37]] 10:53, 5 September 2024 (UTC)

I'm really surprised that "regular slingshot" is "no" for spacecraft instead of something like "not yet". [[User:SystemParadox|SystemParadox]] ([[User talk:SystemParadox|talk]]) 09:46, 5 September 2024 (UTC)
:There's definitely spring-type "delivery systems" (analogues of the elastic slingshots, arguably) which hasten the detatchment of items on a multi-launch 'racked' delivery system. There's also the (proposed, SFAIK not yet tried in anger) rotating-tether release system, akin to biblical sling(shot)s, that would actually be what the gravitational slingshot is most similar to by pure analogy.
:If we ever get a space-elevator and 'drop' things off from the counterweight station, then that would effectively be a biblical slingshot on a planetary scale. (If we time the drop right, or very wrong, with a heavy enough load or even most of the counterweight itself, such that it ends up eventually impacting Earth or any other inhabited lump of rock, it could well also be a matter of a ''planetary'' slingshot with effects on a ''biblical'' scale!) [[Special:Contributions/172.70.86.37|172.70.86.37]] 10:53, 5 September 2024 (UTC)

Gravitational slingshot & Used for Sport shooting would also be a "not yet".
Imagine a couple of millenia from now, where gravitational slingshoting is a sport, and is called shooting for one of many reasons.
ok, fair. It's a stretch. But I felt I had to mention it.
[[Special:Contributions/162.158.222.142|162.158.222.142]] 12:45, 5 September 2024 (UTC)
: In Futurama they use Gravitational slingshot for [https://futurama.fandom.com/wiki/Leo_Wong%27s_%22Miniature%22_Golf_Course "Miniature" golf]

This comic comes the same week as the release of a movie called Slingshot about the gravitational kind.

Isn't David supposed to be using a sling in his fight with Goliath, not a slingshot? That is, a long bit of material that you can use to throw a projectile with higher velocity? There seems to be similar confusion in describing a slingshot as using "mechanical advantage and rotation". A slingshot doesn't really involve rotation, nor does it involve mechanical advantage, really. Mechanical advantage is force amplification, right? And most slingshots don't amplify force, they simply are better than human bodies at delivering that force while moving quickly - that is, they amplify power. Maybe that's splitting hairs. [[Special:Contributions/172.68.71.102|172.68.71.102]] 14:52, 5 September 2024 (UTC)
: I see now that the text has been edited, distinguishing a sling as "an earlier form" of the slingshot. I still don't think that's accurate. They both accelerate a projectile, but they're not at all the same mechanism. Slingshots store deformation energy, and slings store kinetic energy. If we're talking ancient weapons that a slingshot is comparable to, it's far more like a bow than it is a sling. [[Special:Contributions/172.71.22.58|172.71.22.58]] 15:16, 5 September 2024 (UTC)
:: Indeed, the [https://www.etymonline.com/word/slingshot etymologists] tell us that "hand-held implement for throwing stones" is the original meaning of the word "sling", and it dates to 1300. Whereas "slingshot", with "hand catapult" given as a synonym (implying the cleft-stick version), dates only from 1849. The etymologists also tell us that, by the 14th century, "sling" had acquired the additional meaning of "loop for carrying heavy objects", and, by the 18th century, "cloth for suspending an injured arm". These meanings, I argue, gained prominence, while the sling (weapon) fell out of favor, in armies and in language. I daresay that a person with deir arm in a sling would shudder at the prospect of that arm being hurled at an oncoming foe. It appears to me that, at least in the USA where I reside, "slingshot" is now applied to both the "hand catapult" and the "sling (weapon)" to avoid confusion with the sling (object carrier). [[Special:Contributions/172.68.23.190|172.68.23.190]] 15:42, 5 September 2024 (UTC)
::: I'm also in the US, but slingshot to me specifically evokes something where you store and release elastic energy. People often *hear* sling and think it's referring to a slingshot, because they're unfamiliar with an actual sling (weapon). Although slingshot and sling are certainly etymologically related, they are not technologically related. You might argue that a "gravitational slingshot" is a misnomer, in that its arc around a body is more akin to a sling than to a slingshot, I suppose. But a sling is not an earlier form of the "regular slingshot" in this comic. [[Special:Contributions/172.71.31.46|172.71.31.46]] 16:56, 5 September 2024 (UTC)
:: I come from where the Y-Stick-with-rubber-'bowstring' is termed a catapult, and always associated "slingshot" as being the "shot" (projectile) that was slung (either in a David/Golith 'swung sling' or a Dennise The Menace 'pulled elastic' version), where actually deliberately manufactured/harvested beforehand (typically cast lead, as per muskets, or else specific riverbed pebbles) for consistency of mass and convenience of size rather than just relying upon randomly available rocks and stones grabbed from the ground-clutter as and when needed.
:: But when I went looking for references, it seems there's a general merging of terms (apparently also "pea-shooter", among others, although I'd say ''that'' was a short blowpipe/thick straw that a dried pea or pea-sized wad of mashed up paper can be quickly expelled from just by lung-power). And while some 'catapults' might also be the slung type, with the neolithic-era "stout cords and cradle" design, generally the comic-book type (rather than full blown onagers, mangonels or trebuchets) match what both UK and US alternatives of Dennis tend to use, so clearly that's what Randall is talking about. [[Special:Contributions/172.70.91.27|172.70.91.27]] 17:23, 5 September 2024 (UTC)

I vote we use gravitational slingshots to hunt stray probes. Anyone wanna try taking down Voyager I? [[Special:Contributions/172.69.90.237|172.69.90.237]] 14:57, 5 September 2024 (UTC)
:If we fire at Voyager I (or II, especially) and perhaps ''miss'', we then likely set a new record for fastest/furthest object sent out into the universe by man. Win-Win! [[Special:Contributions/172.70.91.27|172.70.91.27]] 17:23, 5 September 2024 (UTC)