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# upthrust

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

«upthrust» in the English dictionary: everyday — its meanings, how the lessons use it, and examples, each with its tree on Mova.

## Everyday

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://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://mova.elamur.ai/free/en/corpora/dictionaries/school/U/upthrust/#m2)

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

## On Mova

- [Trees and pragmatics of «upthrust» in the school dictionary](https://mova.elamur.ai/free/en/corpora/dictionaries/school/U/upthrust/): every meaning and example parsed by Mova, with its dependency tree and frames.
- [«upthrust» in the school dictionary](https://mova.elamur.ai/free/en/dictionaries/school/w/upthrust.html) on Mova free.