Editing 2585: Rounding

Jump to: navigation, search

Warning: You are not logged in. Your IP address will be publicly visible if you make any edits. If you log in or create an account, your edits will be attributed to your username, along with other benefits.

The edit can be undone. Please check the comparison below to verify that this is what you want to do, and then save the changes below to finish undoing the edit.
Latest revision Your text
Line 10: Line 10:
 
This comic is about the follies of unit conversion. Normally, when you say you can ride a bike at 45 {{w|Miles per hour|mph}} if you round, you mean that you can ride at a speed between 44.5 and 45.5, something most people are incapable of doing.{{Citation needed}} The joke is that Cueball actually means if you go through a extremely long chain of rounding imprecisely (see [[#Table of rounding|below]]), starting at 17 mph (which is equivalent to 27.4 km/h and not an improbable speed for an ordinary road-bike and a reasonably fit rider), you can get to the value of 45 (72.4 km/h).
 
This comic is about the follies of unit conversion. Normally, when you say you can ride a bike at 45 {{w|Miles per hour|mph}} if you round, you mean that you can ride at a speed between 44.5 and 45.5, something most people are incapable of doing.{{Citation needed}} The joke is that Cueball actually means if you go through a extremely long chain of rounding imprecisely (see [[#Table of rounding|below]]), starting at 17 mph (which is equivalent to 27.4 km/h and not an improbable speed for an ordinary road-bike and a reasonably fit rider), you can get to the value of 45 (72.4 km/h).
  
βˆ’
Randall also esoterically uses some more historic units here: fathoms/sec, furlongs/min, and furlongs/hr. A {{w|fathom}} is a unit of length, in the modern era being equivalent to six feet, usually used to measure the depth of water. Fathoms/sec could potentially be used to measure the ascent/descent speed of a submersible, but it would normally be a strange choice to enumerate the speed of a bike. A {{w|furlong}} is also a unit of length, equivalent to one eighth of a mile (or 660 feet or 110 fathoms) but is mostly unused except in horse racing. It is possible that furlongs/min or furlongs/hour could be used to measure the speed of a horse. {{w|Knot (unit)|Knot}}s (nautical miles per hour) are a standard unit of measuring speed, but are typically used for measuring speed for airplanes or ships, not speed on land. However, km/h (kilometers per hour, spelled kph in the comic) is commonly used internationally to state the speed of land vehicles, while m/s (meters per second) is a measurement encountered in scientific usage.
+
Randall also esoterically uses some more historic units here: fathoms/sec, furlongs/min, and furlongs/hr. A {{w|fathom}} is a unit of length, in the modern era being equivalent to six feet, usually used to measure the depth of water. Fathoms/sec could potentially be used to measure the ascent/descent speed of a submersible, but it would normally be a strange choice to enumerate the speed of a bike. A {{w|furlong}} is also a unit of length, there are eight to the mile (each of which is 660 feet or 110 fathoms) but is mostly unused except in horse racing. It is possible that furlongs/min or furlongs/hour could be used to measure the speed of a horse. {{w|Knot (unit)|Knot}}s (nautical miles per hour) are a standard unit of measuring speed, but are typically used for measuring speed for airplanes or ships, not speed on land. However, km/h (kilometers per hour, spelled kph in the comic) is commonly used internationally to state the speed of land vehicles, while m/s (meters per second) is a measurement encountered in scientific usage.
  
 
The title text furthers the joke by taking the imprecise rounding literally, implying that this increase could actually be used/abused as a novel form of propulsion, but it isn't clarified for what type of vehicle. It could be an engine for ground or air travel, but contains the implication that it is trying to 'trick physics' similar to the {{w|Alcubierre drive|theoretical 'warp drive'}} conceived to propel interstellar spacecraft at otherwise impossible speeds. One interpretation of the supposed chain of conversions is that it has somehow created a great deal of energy from nothing. Suppose there existed a device or system that could magically accelerate an object from 17 mph to 45 mph without any energy input. The sped-up object could be harnessed to a generator or engine in such a way that the object was slowed back down to 17 mph, with the difference in energy being output in a useful way, and the object fed back into the device. The result would be an engine that could create both free energy and non-conserved changes in momentum.
 
The title text furthers the joke by taking the imprecise rounding literally, implying that this increase could actually be used/abused as a novel form of propulsion, but it isn't clarified for what type of vehicle. It could be an engine for ground or air travel, but contains the implication that it is trying to 'trick physics' similar to the {{w|Alcubierre drive|theoretical 'warp drive'}} conceived to propel interstellar spacecraft at otherwise impossible speeds. One interpretation of the supposed chain of conversions is that it has somehow created a great deal of energy from nothing. Suppose there existed a device or system that could magically accelerate an object from 17 mph to 45 mph without any energy input. The sped-up object could be harnessed to a generator or engine in such a way that the object was slowed back down to 17 mph, with the difference in energy being output in a useful way, and the object fed back into the device. The result would be an engine that could create both free energy and non-conserved changes in momentum.

Please note that all contributions to explain xkcd may be edited, altered, or removed by other contributors. If you do not want your writing to be edited mercilessly, then do not submit it here.
You are also promising us that you wrote this yourself, or copied it from a public domain or similar free resource (see explain xkcd:Copyrights for details). Do not submit copyrighted work without permission!

To protect the wiki against automated edit spam, we kindly ask you to solve the following CAPTCHA:

Cancel | Editing help (opens in new window)