Editing Suction

{{short description|Air pressure differential between two areas}}
{{other uses|suction (medicine)|suction convention}}

{{Multiple issues|
{{More citations needed|date=January 2024}}
{{Original research|date=December 2022}}
}}
[[File:Suction vs Blowing.png|thumb|240x240px|Gasses or liquids that move along a pressure gradient can exert forces on objects. Objects can only be pushed by gases or liquids. The correct terminology used depends on whether they are pushed from a pressurized zone towards ambient pressure (blown out) or from ambient pressure towards a low pressure zone (sucked in). Gases and liquids cannot generate pulling forces on objects.<ref>{{Cite web |last=Quora |title=There's No Suction In Space, Because Suction Is An Illusion |url=https://www.forbes.com/sites/quora/2016/11/21/theres-no-suction-in-space-because-suction-is-an-illusion/ |access-date=2024-01-16 |website=Forbes |language=en}}</ref>]]
'''Suction''' is the day-to-day term for the movement of [[gas]]es or [[liquid]]s along a [[pressure]] gradient with the implication that the movement occurs because the lower pressure pulls the gas or liquid. However, the forces acting in this case do not originate from just the lower pressure side, but also from the side of the higher pressure, as a reaction to the pressure difference.

When the pressure in one part of a [[physical system]] is reduced relative to another, the [[fluid]] or gas in the higher pressure region will exert a [[force]] relative to the region of lowered pressure, referred to as [[pressure-gradient force]]. If all gas or fluid is removed the result is a perfect vacuum in which the pressure is zero. Hence, no negative pressure forces can be generated. Accordingly, from a physics point of view, the objects are not  pulled but pushed.

== Examples ==
Pressure reduction may be [[Static pressure|static]], as in a [[piston]] and cylinder arrangement, or [[Dynamic pressure|dynamic]], as in the case of a [[vacuum cleaner]] when air flow results in a reduced pressure region.

When animals breathe, the [[Thoracic diaphragm|diaphragm]] and muscles around the rib cage cause a change of volume in the lungs. The increased volume of the [[chest cavity]] decreases the pressure inside, creating an imbalance with the ambient air pressure, resulting in suction. Similarly, when a straw is used to suck a liquid from a glass into the mouth, the atmospheric pressure on the fluid in the glass pushes the liquid up through the straw along the pressure gradient.

A common semantic mistake in aviation accident reporting is describing people or objects as being 'sucked out' during [[Uncontrolled decompression|rapid decompression]] events, when physically they are 'blown out' by the higher internal cabin pressure rushing toward the lower ambient pressure outside the plane — the opposite phenomenon to what happens when an object is placed too close to a running jet engine creating the risk of being sucked in.<ref>{{Cite web |last=Quora |title=There's No Suction In Space, Because Suction Is An Illusion |url=https://www.forbes.com/sites/quora/2016/11/21/theres-no-suction-in-space-because-suction-is-an-illusion/ |access-date=2024-01-14 |website=Forbes |language=en}}</ref><ref>{{Cite web |title=Why doesn't Earth's atmosphere escape into space? |url=https://www.spacecentre.nz/resources/faq/solar-system/earth/atmosphere-escape.html |access-date=2024-01-14 |website=www.spacecentre.nz}}</ref><ref>{{Cite web |title=NTSB Schedules Investigative Hearing on Boeing 737-9 MAX Door Plug Blowout |url=https://www.ntsb.gov/news/press-releases/Pages/NR20240312.aspx |access-date=2025-03-19 |website=www.ntsb.gov}}</ref>

== See also ==
{{Wiktionary}}
*[[Pump]]
*[[Vacuum pump]]
*[[Suction (medicine)|Suction devices used in medicine]]
*[[Implosion (mechanical process)|Implosion]]
* [[Suction cup]]
* [[Suction cupping]]

== References ==
{{reflist}}

[[Category:Physical quantities]]
[[Category:Units of pressure]]
[[Category:Vacuum]]