--- title: Floating in the real world: ice, submarines and balloons — a lesson of Mova's school · trees and pragmatics description: «Floating in the real world: ice, submarines and balloons», a lesson of the physics course of Mova's primary school, sentence by sentence with dependency trees and pragmatics. It begins: The rule of floating works for ice, oil, ships and even air: whatever is lighter for its size rises above whateve --- [Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/physics/12-ice-submarines-and-balloons/) [home](https://md.mova.elamur.ai/free/en/) / [corpora](https://md.mova.elamur.ai/free/en/corpora/) / [school](https://md.mova.elamur.ai/free/en/corpora/school/) / [Physics](https://md.mova.elamur.ai/free/en/corpora/school/physics/) / Floating in the real world: ice, subma… # Floating in the real world: ice, submarines and balloons Lesson 12 of the physics course of Mova's primary school: 16 sentences, each with its syntax tree and pragmatics. The lessons are written for Mova, and their agreed trees are part of Mova corpus 0.4 (CC BY-SA 4.0). How Mova does on its tests: [the lesson at school](https://md.mova.elamur.ai/free/en/school-run/physics/12-ice-submarines-and-balloons/). - [0](https://md.mova.elamur.ai/free/en/corpora/school/physics/12-ice-submarines-and-balloons/0/) — The rule of floating works for ice, oil, ships and even air: whatever is lighter for its size rises above whatever is heavier for its size. - [1](https://md.mova.elamur.ai/free/en/corpora/school/physics/12-ice-submarines-and-balloons/1/) — Water is strange: it grows bigger when it freezes, so ice is lighter for its size than water and floats, which saves fish in frozen ponds. - [2](https://md.mova.elamur.ai/free/en/corpora/school/physics/12-ice-submarines-and-balloons/2/) — Air pushes up just like water, only more gently, so a helium balloon or a hot-air balloon floats in the air like wood floats in a pond. - [3](https://md.mova.elamur.ai/free/en/corpora/school/physics/12-ice-submarines-and-balloons/3/) — Some tiny things do not float at all but rest on the water's surface, which behaves like a thin stretchy skin: that is how a pond skater walks on water. - [5](https://md.mova.elamur.ai/free/en/corpora/school/physics/12-ice-submarines-and-balloons/5/) — If ice sank, ponds would freeze from the bottom up and fish could not survive the winter. - [6](https://md.mova.elamur.ai/free/en/corpora/school/physics/12-ice-submarines-and-balloons/6/) — About nine tenths of an iceberg is hidden below the sea, which is why ships keep far away, as the Titanic found out in 1912. - [7](https://md.mova.elamur.ai/free/en/corpora/school/physics/12-ice-submarines-and-balloons/7/) — A submarine fills tanks with seawater to sink and blows them out with air to rise. - [8](https://md.mova.elamur.ai/free/en/corpora/school/physics/12-ice-submarines-and-balloons/8/) — Fish use a similar trick with a little bag of gas inside them, called a swim bladder. - [9](https://md.mova.elamur.ai/free/en/corpora/school/physics/12-ice-submarines-and-balloons/9/) — Helium is much lighter than air, so the air pushes a helium balloon up; let go outside, it rises until it pops, and balloons can harm wildlife. - [10](https://md.mova.elamur.ai/free/en/corpora/school/physics/12-ice-submarines-and-balloons/10/) — Hot air spreads out and gets lighter for its size than the cold air around it, so a hot-air balloon rises, and sinks slowly as the air inside cools, so the pilot fires a burner to heat it again. - [11](https://md.mova.elamur.ai/free/en/corpora/school/physics/12-ice-submarines-and-balloons/11/) — Oil is lighter than water for its size and does not mix with it, so spilled oil spreads over the sea and coats birds' feathers. - [12](https://md.mova.elamur.ai/free/en/corpora/school/physics/12-ice-submarines-and-balloons/12/) — A can of normal cola sinks and a can of diet cola floats, because the sugar in normal cola makes it a little heavier. - [13](https://md.mova.elamur.ai/free/en/corpora/school/physics/12-ice-submarines-and-balloons/13/) — The surface of water acts like a thin stretchy skin, because water molecules hold tightly together at the top. - [14](https://md.mova.elamur.ai/free/en/corpora/school/physics/12-ice-submarines-and-balloons/14/) — A pond skater's light, waxy feet do not break the water's skin, and a drop of washing-up liquid weakens the skin so a resting paper clip sinks at once. - [15](https://md.mova.elamur.ai/free/en/corpora/school/physics/12-ice-submarines-and-balloons/15/) — A steel paper clip placed gently rests on the water's skin; it is not floating like a boat, and pushed through the skin it sinks. - [16](https://md.mova.elamur.ai/free/en/corpora/school/physics/12-ice-submarines-and-balloons/16/) — Sealed plastic bottles are full of air, so a raft of many bottles can hold up a child, but people on such rafts should still wear life jackets. - ← previous: [Floating and sinking: the push of the water](https://md.mova.elamur.ai/free/en/corpora/school/physics/11-floating-and-sinking/) - next →: [Water safety and the ocean](https://md.mova.elamur.ai/free/en/corpora/school/physics/13-water-safety-and-the-ocean/) - ↑ back to [Physics](https://md.mova.elamur.ai/free/en/corpora/school/physics/)