Home › Engineering & Industrial Design › Fluid Dynamics & Hydraulics › displacement

displacement

dis-PLAYS-muhnt /dɪsˈpleɪs.mənt/

nounB2SATACTTOEFLIELTS

generaltechnical

The volume or weight of fluid displaced by a floating or submerged body.

In fluid dynamics, it refers specifically to the fluid pushed aside by an object, which determines the buoyant force.

The story behind the word. Formed from the prefix 'dis-' (expressing removal) and 'place' (from Greek 'plateia', meaning a broad street or open space). It literally means to force something out of its proper place, which is exactly what a boat hull does to ocean water.

Word relationships

eviction: Eviction is the legal removal of a person, whereas displacement in physics is the physical pushing aside of fluid or matter.

Commonly confused with

volume: Volume is the total space an object occupies, while displacement is the specific volume of fluid pushed aside by that object.

Word family

displace (verb): To take the place of; to push out of position.

Collocations

water displacement
engine displacement
displacement tonnage
calculate displacement

Example sentences

"The aircraft carrier has a displacement of over 100,000 tons, meaning it pushes aside that exact weight of seawater." Naval architecture
"Archimedes discovered the principle of displacement while taking a bath, realizing the water level rose as he submerged." Classical science history

Memory hook

Think of 'dis-placement' as 'dis-placing' (removing) water from its original spot. Displacement = Dis-placing water.

When not to use

Do not confuse with simple distance traveled, although 'displacement' is also used in physics to mean straight-line distance.

Fun facts

Archimedes was so excited when he discovered fluid displacement that he allegedly ran naked through the streets of Syracuse shouting 'Eureka!' ('I have found it!').