--- title: Olympiad: forces, floating and machines ★★★ — a lesson of Mova's school · trees and pragmatics description: «Olympiad: forces, floating and machines ★★★», a lesson of the physics course of Mova's primary school, sentence by sentence with dependency trees and pragmatics. It begins: This olympiad block closes the course: each puzzle hides one sharp idea from the earlier lessons, and the trick is to find whi --- [Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/physics/42-olympiad-forces-floating-and-machines/) [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/) / Olympiad: forces, floating and machine… # Olympiad: forces, floating and machines ★★★ Lesson 42 of the physics course of Mova's primary school: 17 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/42-olympiad-forces-floating-and-machines/). - [0](https://md.mova.elamur.ai/free/en/corpora/school/physics/42-olympiad-forces-floating-and-machines/0/) — This olympiad block closes the course: each puzzle hides one sharp idea from the earlier lessons, and the trick is to find which idea it is before you start counting. - [1](https://md.mova.elamur.ai/free/en/corpora/school/physics/42-olympiad-forces-floating-and-machines/1/) — Many puzzles take a rule you know into a new place: a seesaw, a wheelbarrow and a nutcracker are all levers, so one rule, far from the pivot is easier, cracks all three. - [2](https://md.mova.elamur.ai/free/en/corpora/school/physics/42-olympiad-forces-floating-and-machines/2/) — Some puzzles hide a trap in the words: "Which is heavier, a kilogram of feathers or a kilogram of stones?" Neither, both weigh a kilogram, though the feathers fill far more room. - [3](https://md.mova.elamur.ai/free/en/corpora/school/physics/42-olympiad-forces-floating-and-machines/3/) — Gear puzzles are about counting: two meshing gears turn opposite ways, so in a row the 1st, 3rd and 5th gears turn like the first one, and three gears meshing in a closed ring jam. - [4](https://md.mova.elamur.ai/free/en/corpora/school/physics/42-olympiad-forces-floating-and-machines/4/) — Picture Jaz from Yorkshire groaning "This box weighs a ton, I'm literally dying, our kid": "our kid" means my brother, and the ton and the dying are hyperbole, a heavy box and a tired boy, which a pulley can help. - [5](https://md.mova.elamur.ai/free/en/corpora/school/physics/42-olympiad-forces-floating-and-machines/5/) — Two meshing gears turn in opposite directions, so in a row of gears the odd-numbered ones turn like the first and the even-numbered ones turn the other way. - [6](https://md.mova.elamur.ai/free/en/corpora/school/physics/42-olympiad-forces-floating-and-machines/6/) — Three gears that all mesh with one another in a ring cannot turn at all, because each would have to turn both ways at once. - [7](https://md.mova.elamur.ai/free/en/corpora/school/physics/42-olympiad-forces-floating-and-machines/7/) — A gear with 30 teeth that turns once pushes 30 teeth of the gear it meshes with, so a 10-tooth gear turns 3 times. - [8](https://md.mova.elamur.ai/free/en/corpora/school/physics/42-olympiad-forces-floating-and-machines/8/) — A seesaw balances when the heavier person sits closer in: someone twice as heavy balances at half the distance from the middle. - [9](https://md.mova.elamur.ai/free/en/corpora/school/physics/42-olympiad-forces-floating-and-machines/9/) — If 4 lengths of rope hold a load in a set of pulleys, you pull with about a quarter of the force, but you must pull 4 metres of rope to lift the load 1 metre. - [10](https://md.mova.elamur.ai/free/en/corpora/school/physics/42-olympiad-forces-floating-and-machines/10/) — On the Moon, bathroom scales would show about one sixth of what they show on Earth, but your mass, the stuff you are made of, stays the same. - [11](https://md.mova.elamur.ai/free/en/corpora/school/physics/42-olympiad-forces-floating-and-machines/11/) — A kilogram of feathers and a kilogram of stones weigh the same, but the feathers take up much more room. - [12](https://md.mova.elamur.ai/free/en/corpora/school/physics/42-olympiad-forces-floating-and-machines/12/) — When a ship sails from a river into the salty sea, it floats a little higher, because salty water pushes up harder. - [13](https://md.mova.elamur.ai/free/en/corpora/school/physics/42-olympiad-forces-floating-and-machines/13/) — An ice cube floating in a glass filled to the brim does not make it overflow as it melts: the melted water just fills the space the ice was taking up under the surface. - [14](https://md.mova.elamur.ai/free/en/corpora/school/physics/42-olympiad-forces-floating-and-machines/14/) — A pendulum four times as long takes twice as long to swing, so a clock that runs slow is mended by moving the weight up to shorten the pendulum. - [15](https://md.mova.elamur.ai/free/en/corpora/school/physics/42-olympiad-forces-floating-and-machines/15/) — A tennis ball and a golf ball dropped together from a table land at about the same time, but a flat sheet of paper drifts down far more slowly because the air slows it much more. - [16](https://md.mova.elamur.ai/free/en/corpora/school/physics/42-olympiad-forces-floating-and-machines/16/) — "This weighs a ton" is hyperbole: a ton is 1,000 kilograms, about as much as a small car, and no school bag or box a child can carry weighs that. - ← previous: [Alice's fall and her sizes: falling, the centre of the Earth, giants and tiny people](https://md.mova.elamur.ai/free/en/corpora/school/physics/41-alice-s-fall-and-sizes-falling-the-centre-of-the-earth-giants-and-tiny-people/) - next →: [Olympiad: sound, light, heat, electricity and magnets ★★★](https://md.mova.elamur.ai/free/en/corpora/school/physics/43-olympiad-sound-light-heat-and-magnets/) - ↑ back to [Physics](https://md.mova.elamur.ai/free/en/corpora/school/physics/)