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# upthrust

«upthrust» in Mova's school dictionary: **The upward push that a liquid or gas gives to an object…** — its meaning for a pupil, its sense in the lessons and examples, with 5 sentences of Mova's corpora that use it.

### part of speech

noun (upthrust, uncountable; sometimes «an upthrust»)

### meaning for a pupil

1) (science) The upward push that a liquid or gas gives to an object placed in it; it is why things float or feel lighter in water. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/U/upthrust/#m1)

2) (geography) A pushing upward of rock or land, for example when mountains slowly rise. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/U/upthrust/#m2)

### sense in the lessons

Used in school science lessons about floating and sinking, forces and density. If the upthrust is equal to the object's weight, the object floats; if the weight is bigger, it sinks. Often drawn as an arrow pointing up on a force diagram. Phrases: «upthrust and weight», «the upthrust on the boat».

### examples

- The water gives the boat an upthrust. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/U/upthrust/#x1)
- A ball feels lighter in the pool because of upthrust. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/U/upthrust/#x2)
- Draw an arrow to show the upthrust on the cork. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/U/upthrust/#x3)
- If the upthrust equals the weight, the object floats. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/U/upthrust/#x4)
- A stone sinks because its weight is bigger than the upthrust. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/U/upthrust/#x5)
- Air gives a small upthrust to a balloon. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/U/upthrust/#x6)
- The mountains were formed by an upthrust of rock. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/U/upthrust/#x7)

### note

Mostly UK school science; in the USA it is often called «buoyant force» or «buoyancy». Measured in newtons (N) like other forces. In problems: weight minus upthrust gives the apparent weight in water (a 10 N stone with 3 N upthrust feels like 7 N).

### In the corpora

- [This push is called upthrust.](https://md.mova.elamur.ai/free/en/corpora/school/world/83-floating-and-sinking/1/)
- [Water pushes up on anything placed in it; this push is called upthrust.](https://md.mova.elamur.ai/free/en/corpora/school/world/83-floating-and-sinking/12/)
- [The upthrust equals the weight of the water that the object pushes aside.](https://md.mova.elamur.ai/free/en/corpora/school/world/83-floating-and-sinking/14/)
- [An object floats when the upthrust is equal to its weight.](https://md.mova.elamur.ai/free/en/corpora/school/world/83-floating-and-sinking/15/)
- [Salt water gives more upthrust than fresh water.](https://md.mova.elamur.ai/free/en/corpora/school/world/83-floating-and-sinking/18/)

### Trees and pragmatics

[Every meaning and example of «upthrust» parsed by Mova](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/U/upthrust/), each sentence with its dependency tree and frames.