| 词条 | Pythagorean cup |
| 释义 |
A Pythagorean cup (also known as a Pythagoras cup, Greedy Cup, Tantalus cup or i koupa tis dikaiosynis) is a practical joke device in a form of a drinking cup, credited to Pythagoras of Samos.{{Citation needed|reason="Credited to Pytahgoras" by whom? What primary reference imputes invention of this cup to Pythagoras?|date=June 2018}} When it is filled beyond a certain point, a siphoning effect causes the cup to drain its entire contents through the base. Form and functionA Pythagorean cup looks like a normal drinking cup, except that the bowl has a central column in it, giving it a shape like a Bundt pan. The central column of the bowl is positioned directly over the stem of the cup and over the hole at the bottom of the stem. A small open pipe runs from this hole almost to the top of the central column, where there is an open chamber. The chamber is connected by a second pipe to the bottom of the central column, where a hole in the column exposes the pipe to (the contents of) the bowl of the cup.[1] When the cup is filled, liquid rises through the second pipe up to the chamber at the top of the central column, following Pascal's principle of communicating vessels. As long as the level of the liquid does not rise beyond the level of the chamber, the cup functions as normal. If the level rises further, however, the liquid spills through the chamber into the first pipe and out the bottom. Gravity then creates a siphon through the central column, causing the entire contents of the cup to be emptied through the hole at the bottom of the stem.[2] Some modern toilets operate on the same principle: when the water level in the bowl rises high enough, a siphon is created, flushing the toilet.{{citation needed|date=September 2017}} See also
References1. ^{{cite web |url = http://skullsinthestars.com/2012/04/26/physics-demonstrations-the-pythagoras-cup/ |title = Physics demonstrations: the Pythagoras cup |date = 2012-04-26 |website = skullinthestars.com |accessdate = 2015-01-30}} 2. ^{{cite web| url=http://www.epmagazine.org/storage/431.aspx| title=Pythagorean cup - The Theory| publisher=EP Magazine| year=2008| issue=2| accessdate=2015-01-30}} External links
6 : Ancient inventions|Drinkware|Fluid dynamics|Practical joke devices|Samos|Wine accessories |
| 随便看 |
|
开放百科全书收录14589846条英语、德语、日语等多语种百科知识，基本涵盖了大多数领域的百科知识，是一部内容自由、开放的电子版国际百科全书。