2743: Hand Dryers - Revision history

CalibansCreations: /* Explanation */

2025-02-28T14:26:43Z

‎Explanation

Jkshapiro: /* Explanation */ General cleanup

2024-01-07T16:20:54Z

‎Explanation: General cleanup

Jkshapiro: /* Explanation */ No explanation needed

2024-01-07T15:58:21Z

‎Explanation: No explanation needed

Jkshapiro: Undo https://www.explainxkcd.com/wiki/index.php?title=2743:_Hand_Dryers&curid=26082&diff=307149&oldid=307043

2024-01-07T15:57:39Z

Undo https://www.explainxkcd.com/wiki/index.php?title=2743:_Hand_Dryers&curid=26082&diff=307149&oldid=307043

172.71.250.27: /* Explanation */ The citation is provided by the linked "speed of sound" wikipedia article.

2023-04-28T10:30:44Z

‎Explanation: The citation is provided by the linked "speed of sound" wikipedia article.

172.71.147.80: /* Transcript */

2023-04-06T15:01:44Z

‎Transcript

Xurkitree10: /* Explanation */

2023-03-27T20:21:38Z

‎Explanation

108.162.245.186 at 11:35, 13 March 2023

2023-03-13T11:35:24Z

Gunterkoenigsmann: /* Explanation: The rationale behind increasing the air flow until it hits a limit */

2023-03-02T19:02:17Z

‎Explanation: The rationale behind increasing the air flow until it hits a limit

SilverTheTerribleMathematician: /* Explanation */

2023-03-01T15:10:43Z

‎Explanation

@@ Line 12: / Line 12: @@
 A {{w|hand dryer}} is an electrical device which uses air flow, typically of hot air, to dry the user's hands after they have just washed them. In the 30 or so seconds it takes to dry the hands, the user may feel as though the air coming from the hand dryer isn't actually warm, hence seeming like they "take forever to heat up."
-Randall is pointing out that {{w|evaporation}} is an endothermic process, which is why sweating cools you down and therefore why regular fans, which actually increase the air temperature through friction, can cause a cooling effect. With hand dryers, even though the air is warm, the cooling effect makes it feel cold. The user will be able to feel the heat only after their hands are dry.
+[[Randall]] is pointing out that {{w|evaporation}} is an endothermic process, which is why sweating cools you down and therefore why regular fans, which actually increase the air temperature through friction, can cause a cooling effect. With hand dryers, even though the air is warm, the cooling effect makes it feel cold. The user will be able to feel the heat only after their hands are dry.
 Randall has procured a small airplane, accompanied by a banner with a message explaining this phenomenon. He elaborates in the caption that he's spent dozens of years angry at the engineers of these hand dryers, as he was under the comic's erroneous impression that the air from the dryers was not actually warm. In an act of justice for hand dryer engineers everywhere, he now considers it his personal mission to explain to the public why this is actually a misconception. And indeed, it seems to be working - a person on the ground has already been [[1053: Ten Thousand|enlightened]] by Randall.

@@ Line 10: / Line 10: @@
 ==Explanation==
-A {{w|hand dryer}} is an electrical device which uses air flow, typically of hot air, to dry the user's hands after they have just washed them. In the 30 or so seconds it takes to dry the hands, the user may feel as though the air coming from the hand dryer isn't actually warm, hence seeming like they "take forever to heat up," while in reality the water evaporating from the user's wet hands absorbs heat from them, as well as the possibly heated air, as {{w|evaporation}} is an endothermic process. Thus the user does not ''feel'' that the air from the dryer is warm, even though it is, and will only start to do so once their hands have been significantly dried. Interestingly, this absorption of heat through evaporation is how human {{w|sweat}} has its cooling effect, which means that even warm ambient air can be made to feel colder by being wafted across a person's dampened skin (which is how a regular fan works).
+A {{w|hand dryer}} is an electrical device which uses air flow, typically of hot air, to dry the user's hands after they have just washed them. In the 30 or so seconds it takes to dry the hands, the user may feel as though the air coming from the hand dryer isn't actually warm, hence seeming like they "take forever to heat up."
 Randall has procured a small airplane, accompanied by a banner with a message explaining this phenomenon. He elaborates in the caption that he's spent dozens of years angry at the engineers of these hand dryers, as he was under the comic's erroneous impression that the air from the dryers was not actually warm. In an act of justice for hand dryer engineers everywhere, he now considers it his personal mission to explain to the public why this is actually a misconception. And indeed, it seems to be working - a person on the ground has already been [[1053: Ten Thousand|enlightened]] by Randall.
-In the title text, the {{w|speed of sound}} is the speed of a sound wave in a given medium, usually air. Breaking the {{w|sound barrier}} is often touted as a significant achievement for powered aircraft (this was first safely achieved in the 1940s, and became significantly 'easier' with the development of the jet engine). Here, Randall thinks it would be a good idea to try and get the {{w|Dyson (company)|Dyson company}} (a technology company known for making high-tech, fancy and expensive air-moving devices such as vacuum-cleaners, fans and hand dryers) to design a hand dryer whose airflow would exceed the sound barrier. This would be technically difficult to achieve with such a relatively small device as a typical wall-mounted hand dryer {{Citation needed}}. Nor would such a hand dryer really be practically useful, given that air currents faster than the speed of sound could cause injury to the hands of the dryer's users,{{Citation needed}} amongst other unintended effects.
+In the title text, the {{w|speed of sound}} is the speed of a sound wave in a given medium, usually air. Breaking the {{w|sound barrier}} is often touted as a significant achievement for powered aircraft (this was first safely achieved in the 1940s, and became significantly 'easier' with the development of the jet engine). Here, Randall thinks it would be a good idea to try and get the {{w|Dyson (company)|Dyson company}} (a technology company known for making high-tech and expensive air-moving devices) to design a hand dryer whose airflow would exceed the sound barrier. Dyson's marketing often turns on the very high speed of the airflow produced by their motors, often many hundreds of kilometres per hour, indeed approaching the speed of sound. However, there are side effects of supersonic airflow, including {{w|sonic booms}}, which would make it impractical for purposes of drying hands in an enclosed area.
-This comic is not the only one to involve people flying banner planes to inform people on technologically related things, as that was previous done in a (lengthier) [[1965: Background Apps]].
+This comic is not the only one to involve people flying banner planes to inform people on technologically related things: see also [[1965: Background Apps]].
 ==Transcript==

@@ Line 10: / Line 10: @@
 ==Explanation==
-A {{w|hand dryer}} is an electrical device which uses air flow, typically of hot air, to dry the user's hands after they have just washed them. In the 30 or so seconds it takes to dry the hands, the user may feel as though the air coming from the hand dryer isn't actually warm,{{citation needed}} hence seeming like they "take forever to heat up," while in reality the water evaporating from the user's wet hands absorbs heat from them, as well as the possibly heated air, as {{w|evaporation}} is an endothermic process. Thus the user does not ''feel'' that the air from the dryer is warm, even though it is, and will only start to do so once their hands have been significantly dried. Interestingly, this absorption of heat through evaporation is how human {{w|sweat}} has its cooling effect, which means that even warm ambient air can be made to feel colder by being wafted across a person's dampened skin (which is how a regular fan works).
+A {{w|hand dryer}} is an electrical device which uses air flow, typically of hot air, to dry the user's hands after they have just washed them. In the 30 or so seconds it takes to dry the hands, the user may feel as though the air coming from the hand dryer isn't actually warm, hence seeming like they "take forever to heat up," while in reality the water evaporating from the user's wet hands absorbs heat from them, as well as the possibly heated air, as {{w|evaporation}} is an endothermic process. Thus the user does not ''feel'' that the air from the dryer is warm, even though it is, and will only start to do so once their hands have been significantly dried. Interestingly, this absorption of heat through evaporation is how human {{w|sweat}} has its cooling effect, which means that even warm ambient air can be made to feel colder by being wafted across a person's dampened skin (which is how a regular fan works).
 Randall has procured a small airplane, accompanied by a banner with a message explaining this phenomenon. He elaborates in the caption that he's spent dozens of years angry at the engineers of these hand dryers, as he was under the comic's erroneous impression that the air from the dryers was not actually warm. In an act of justice for hand dryer engineers everywhere, he now considers it his personal mission to explain to the public why this is actually a misconception. And indeed, it seems to be working - a person on the ground has already been [[1053: Ten Thousand|enlightened]] by Randall.

@@ Line 14: / Line 14: @@
 Randall has procured a small airplane, accompanied by a banner with a message explaining this phenomenon. He elaborates in the caption that he's spent dozens of years angry at the engineers of these hand dryers, as he was under the comic's erroneous impression that the air from the dryers was not actually warm. In an act of justice for hand dryer engineers everywhere, he now considers it his personal mission to explain to the public why this is actually a misconception. And indeed, it seems to be working - a person on the ground has already been [[1053: Ten Thousand|enlightened]] by Randall.
-In the title text, the {{w|speed of sound}} is the speed of a sound wave in a given medium, usually air. Breaking the {{w|sound barrier}} is often touted as a significant achievement for powered aircraft (this was first safely achieved in the 1940s, and became significantly 'easier' with the development of the jet engine). Here, Randall thinks it would be a good idea to continue to complain that all hand dryers take too long to heat up in order to try and get the {{w|Dyson (company)|Dyson company}} (a technology company known for making high-tech, fancy and expensive air-moving devices such as vacuum-cleaners, fans and hand dryers) to design a hand dryer whose airflow would exceed the sound barrier. The rationale behind that might be that the temperature of the air the hand dryer emits cannot be increased much without harming the user. Therefore the only way to make the hands feel warm earlier would be increasing the airflow until (if we tease the Dyson company long enough) they hit a physical limit. Hitting this limit would be technically difficult to achieve with such a relatively small device as a typical wall-mounted hand dryer {{Citation needed}}. Nor would such a hand dryer really be practically useful, given that air currents faster than the speed of sound could cause injury to the hands of the dryer's users,{{Citation needed}} amongst other unintended effects.
+In the title text, the {{w|speed of sound}} is the speed of a sound wave in a given medium, usually air. Breaking the {{w|sound barrier}} is often touted as a significant achievement for powered aircraft (this was first safely achieved in the 1940s, and became significantly 'easier' with the development of the jet engine). Here, Randall thinks it would be a good idea to try and get the {{w|Dyson (company)|Dyson company}} (a technology company known for making high-tech, fancy and expensive air-moving devices such as vacuum-cleaners, fans and hand dryers) to design a hand dryer whose airflow would exceed the sound barrier. This would be technically difficult to achieve with such a relatively small device as a typical wall-mounted hand dryer {{Citation needed}}. Nor would such a hand dryer really be practically useful, given that air currents faster than the speed of sound could cause injury to the hands of the dryer's users,{{Citation needed}} amongst other unintended effects.
 This comic is not the only one to involve people flying banner planes to inform people on technologically related things, as that was previous done in a (lengthier) [[1965: Background Apps]].

@@ Line 14: / Line 14: @@
 Randall has procured a small airplane, accompanied by a banner with a message explaining this phenomenon. He elaborates in the caption that he's spent dozens of years angry at the engineers of these hand dryers, as he was under the comic's erroneous impression that the air from the dryers was not actually warm. In an act of justice for hand dryer engineers everywhere, he now considers it his personal mission to explain to the public why this is actually a misconception. And indeed, it seems to be working - a person on the ground has already been [[1053: Ten Thousand|enlightened]] by Randall.
-In the title text, the {{w|speed of sound}} is the speed of a sound wave{{citation needed}} in a given medium, usually air. Breaking the {{w|sound barrier}} is often touted as a significant achievement for powered aircraft (this was first safely achieved in the 1940s, and became significantly 'easier' with the development of the jet engine). Here, Randall thinks it would be a good idea to continue to complain that all hand dryers take too long to heat up in order to try and get the {{w|Dyson (company)|Dyson company}} (a technology company known for making high-tech, fancy and expensive air-moving devices such as vacuum-cleaners, fans and hand dryers) to design a hand dryer whose airflow would exceed the sound barrier. The rationale behind that might be that the temperature of the air the hand dryer emits cannot be increased much without harming the user. Therefore the only way to make the hands feel warm earlier would be increasing the airflow until (if we tease the Dyson company long enough) they hit a physical limit. Hitting this limit would be technically difficult to achieve with such a relatively small device as a typical wall-mounted hand dryer {{Citation needed}}. Nor would such a hand dryer really be practically useful, given that air currents faster than the speed of sound could cause injury to the hands of the dryer's users,{{Citation needed}} amongst other unintended effects.
+In the title text, the {{w|speed of sound}} is the speed of a sound wave in a given medium, usually air. Breaking the {{w|sound barrier}} is often touted as a significant achievement for powered aircraft (this was first safely achieved in the 1940s, and became significantly 'easier' with the development of the jet engine). Here, Randall thinks it would be a good idea to continue to complain that all hand dryers take too long to heat up in order to try and get the {{w|Dyson (company)|Dyson company}} (a technology company known for making high-tech, fancy and expensive air-moving devices such as vacuum-cleaners, fans and hand dryers) to design a hand dryer whose airflow would exceed the sound barrier. The rationale behind that might be that the temperature of the air the hand dryer emits cannot be increased much without harming the user. Therefore the only way to make the hands feel warm earlier would be increasing the airflow until (if we tease the Dyson company long enough) they hit a physical limit. Hitting this limit would be technically difficult to achieve with such a relatively small device as a typical wall-mounted hand dryer {{Citation needed}}. Nor would such a hand dryer really be practically useful, given that air currents faster than the speed of sound could cause injury to the hands of the dryer's users,{{Citation needed}} amongst other unintended effects.
 This comic is not the only one to involve people flying banner planes to inform people on technologically related things, as that was previous done in a (lengthier) [[1965: Background Apps]].

← Older revision		Revision as of 15:01, 6 April 2023
Line 19:		Line 19:

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

	:[An airplane tows a banner. In the distance, there are three small clouds and three birds]		:[An airplane tows a banner. In the distance, there are three small clouds and three birds]

← Older revision		Revision as of 20:21, 27 March 2023
Line 10:		Line 10:

	==Explanation==		==Explanation==
−	~~{{incomplete\|Created by a DYSON ENGINEER - Please change this comment when editing this page. Do NOT delete this tag too soon.}}~~
	A {{w\|hand dryer}} is an electrical device which uses air flow, typically of hot air, to dry the user's hands after they have just washed them. In the 30 or so seconds it takes to dry the hands, the user may feel as though the air coming from the hand dryer isn't actually warm,{{citation needed}} hence seeming like they "take forever to heat up," while in reality the water evaporating from the user's wet hands absorbs heat from them, as well as the possibly heated air, as {{w\|evaporation}} is an endothermic process. Thus the user does not ''feel'' that the air from the dryer is warm, even though it is, and will only start to do so once their hands have been significantly dried. Interestingly, this absorption of heat through evaporation is how human {{w\|sweat}} has its cooling effect, which means that even warm ambient air can be made to feel colder by being wafted across a person's dampened skin (which is how a regular fan works).		A {{w\|hand dryer}} is an electrical device which uses air flow, typically of hot air, to dry the user's hands after they have just washed them. In the 30 or so seconds it takes to dry the hands, the user may feel as though the air coming from the hand dryer isn't actually warm,{{citation needed}} hence seeming like they "take forever to heat up," while in reality the water evaporating from the user's wet hands absorbs heat from them, as well as the possibly heated air, as {{w\|evaporation}} is an endothermic process. Thus the user does not ''feel'' that the air from the dryer is warm, even though it is, and will only start to do so once their hands have been significantly dried. Interestingly, this absorption of heat through evaporation is how human {{w\|sweat}} has its cooling effect, which means that even warm ambient air can be made to feel colder by being wafted across a person's dampened skin (which is how a regular fan works).

@@ Line 15: / Line 15: @@
 Randall has procured a small airplane, accompanied by a banner with a message explaining this phenomenon. He elaborates in the caption that he's spent dozens of years angry at the engineers of these hand dryers, as he was under the comic's erroneous impression that the air from the dryers was not actually warm. In an act of justice for hand dryer engineers everywhere, he now considers it his personal mission to explain to the public why this is actually a misconception. And indeed, it seems to be working - a person on the ground has already been [[1053: Ten Thousand|enlightened]] by Randall.
-In the title text, the {{w|speed of sound}} is the speed of a sound wave{{citation needed}} in a given medium, usually air. Breaking the {{w|sound barrier}} is often touted as a significant achievement for powered aircraft (this was first safely achieved in the 1940s, and became significantly 'easier' with the development of the jet engine). Here, Randall thinks it would be a good idea to try and get the {{w|Dyson (company)|Dyson company}} (a technology company known for making high-tech, fancy and expensive air-moving devices such as vacuum-cleaners, fans and hand dryers) to design a hand dryer whose airflow would exceed the sound barrier. This would be technically difficult to achieve with such a relatively small device as a typical wall-mounted hand dryer. Nor would such a hand dryer really be practically useful, given that air currents faster than the speed of sound could cause injury to the hands of the dryer's users,{{Citation needed}} amongst other unintended effects.
+In the title text, the {{w|speed of sound}} is the speed of a sound wave{{citation needed}} in a given medium, usually air. Breaking the {{w|sound barrier}} is often touted as a significant achievement for powered aircraft (this was first safely achieved in the 1940s, and became significantly 'easier' with the development of the jet engine). Here, Randall thinks it would be a good idea to continue to complain that all hand dryers take too long to heat up in order to try and get the {{w|Dyson (company)|Dyson company}} (a technology company known for making high-tech, fancy and expensive air-moving devices such as vacuum-cleaners, fans and hand dryers) to design a hand dryer whose airflow would exceed the sound barrier. The rationale behind that might be that the temperature of the air the hand dryer emits cannot be increased much without harming the user. Therefore the only way to make the hands feel warm earlier would be increasing the airflow until (if we tease the Dyson company long enough) they hit a physical limit. Hitting this limit would be technically difficult to achieve with such a relatively small device as a typical wall-mounted hand dryer. Nor would such a hand dryer really be practically useful, given that air currents faster than the speed of sound could cause injury to the hands of the dryer's users,{{Citation needed}} amongst other unintended effects.
 This comic is not the only one to involve people flying banner planes to inform people on technologically related things, as that was previous done in a (lengthier) [[1965: Background Apps]].

← Older revision		Revision as of 15:10, 1 March 2023
Line 16:		Line 16:

	In the title text, the {{w\|speed of sound}} is the speed of a sound wave{{citation needed}} in a given medium, usually air. Breaking the {{w\|sound barrier}} is often touted as a significant achievement for powered aircraft (this was first safely achieved in the 1940s, and became significantly 'easier' with the development of the jet engine). Here, Randall thinks it would be a good idea to try and get the {{w\|Dyson (company)\|Dyson company}} (a technology company known for making high-tech, fancy and expensive air-moving devices such as vacuum-cleaners, fans and hand dryers) to design a hand dryer whose airflow would exceed the sound barrier. This would be technically difficult to achieve with such a relatively small device as a typical wall-mounted hand dryer. Nor would such a hand dryer really be practically useful, given that air currents faster than the speed of sound could cause injury to the hands of the dryer's users,{{Citation needed}} amongst other unintended effects.		In the title text, the {{w\|speed of sound}} is the speed of a sound wave{{citation needed}} in a given medium, usually air. Breaking the {{w\|sound barrier}} is often touted as a significant achievement for powered aircraft (this was first safely achieved in the 1940s, and became significantly 'easier' with the development of the jet engine). Here, Randall thinks it would be a good idea to try and get the {{w\|Dyson (company)\|Dyson company}} (a technology company known for making high-tech, fancy and expensive air-moving devices such as vacuum-cleaners, fans and hand dryers) to design a hand dryer whose airflow would exceed the sound barrier. This would be technically difficult to achieve with such a relatively small device as a typical wall-mounted hand dryer. Nor would such a hand dryer really be practically useful, given that air currents faster than the speed of sound could cause injury to the hands of the dryer's users,{{Citation needed}} amongst other unintended effects.
		+
		+	This comic is not the only one to involve people flying banner planes to inform people on technologically related things, as that was previous done in a (lengthier) [[1965: Background Apps]].

	==Transcript==		==Transcript==