Pressure tricks: pumps, tyres and vacuums

Tests: 9 of 11 right · Exam: 0 of 4 right · Kind: ★★ · Understood: 10 of 15 · Run: 2026-10-18, commit f3c23ea72

Lesson 16 of the physics course of Mova's primary school, as Mova's small model took its tests: it had read this lesson and the ones before it and learned from their exercises. Each test shows the options in the order the student saw them, its choice, the right answer, the score of every option and why it chose. The lesson itself, sentence by sentence with trees and pragmatics: the lesson in the corpora.

Every question of this lesson and each of its options parsed by Mova, with trees and pragmatics: the lesson's questions in the corpora.

Test 1 · ★★ · wrong ✗

oi, why's me football all soft now? pumped it up in the house, now it's frosty out

1. Footballs always leak in winter — ← Mova's choice · no support
2. Cold air inside pushes less, so the ball feels softer — ✓ the right answer · no support
3. The frost sucks the air out of it through the leather overnight — no support
4. The ball shrank because the leather froze — no support

Why: No option found support in what it remembers, so it guessed: it took the first option shown. · the question and its options parsed, with trees and pragmatics

Test 2 · ★★ · right ✓

Your friend says a hoover "sucks the dirt in". What would a physicist say?

1. Outside air pushes the dirt in where the pressure is lower — ← Mova's choice · ✓ the right answer · no support
2. The dirt jumps in because it likes the dark — no support
3. Hoovers really pull the dirt with suction rays — no support
4. The dirt is sucked by static only — no support

Why: No option found support in what it remembers, so it guessed: it took the first option shown. · the question and its options parsed, with trees and pragmatics

Test 3 · ★★ · wrong ✗

A camper on a very high mountain says his pasta is still hard after the usual time. What would help?

1. Cook it longer, or use a pressure cooker — ✓ the right answer · no support
2. Take the lid off to trap more heat — no support
3. Turn the water down so it stops bubbling — ← Mova's choice · score 4
4. Put in more salt to make it boil colder — no support

Why: It took the question to ask who or what does it. It chose option 3 with score 4, the only option with support. Its support: lesson 14, line 17: «Your ears pop when the air pressure changes on a plane or in a fast lift, as a little tube lets air through to even out the push on both sides of the eardrum;…», reached through the same lesson line as the sentence the question matched. What matched: it fills the role the question asks for (+3); the same doer «air» (+2). Against it: a different action (counts against) (-1). The right option, 1, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 4 · ★★ · right ✓

Crap, mum shook the cola bottle before handing it to me. What happens if I open it now?

1. Nothing, shaking has no effect — no support
2. The bottle will freeze in your hand — score 2
3. The cola goes flat inside the closed bottle straight away — no support
4. The gas rushes out at once and sprays everywhere — ← Mova's choice · ✓ the right answer · score 11

Why: It took the question to ask what happens next. It chose option 4 with score 11, against 2 for the next best. Its support: lesson 16, line 12: «A fizzy drink has gas squashed into it under high pressure, and when you open it the pressure drops and the gas escapes as bubbles with a hiss; if the bottle w…», reached through what followed the sentence the question matched. What matched: the same action «rush out» (+5); the same doer «gas» (+4); the same property (+2). · the question and its options parsed, with trees and pragmatics

Test 5 · ★★ · right ✓

What would happen if you tried to breathe in with your chest unable to get any bigger?

1. Air would rush in even faster — no support
2. You would breathe through your ears instead — no support
3. No air would come in, because the pressure inside could not drop — ← Mova's choice · ✓ the right answer · score 3
4. Your heart would do the breathing for you — no support

Why: It took the question to ask what happens next. It chose option 3 with score 3, the only option with support. Its support: lesson 16, line 11: «When you breathe in, a muscle under your lungs pulls down, your chest gets bigger, the pressure inside drops, and outside air pushes in.», reached through what followed the sentence the question matched. What matched: the same action «drop» (+5); the same doer «pressure» (+4). Against it: one says «not», the other does not (counts against) (-6). · the question and its options parsed, with trees and pragmatics

Test 6 · ★★ · right ✓

A ketchup bottle gurgles when you stop squeezing. What is happening?

1. It springs back and air is pushed in to fill the space — ← Mova's choice · ✓ the right answer · score 7
2. The bottle is cracking and breaking at the bottom where you squeezed — score 4
3. The ketchup is boiling inside the bottle from the warmth of your hand — no support
4. The ketchup is slowly turning into air and bubbling away inside — no support

Why: It took the question to ask which statement is true. It chose option 1 with score 7, against 4 for the next best. Its support: lesson 16, line 9: «Squeezing a ketchup bottle raises the pressure inside, and a push on a closed bottle spreads to every part, so the sauce is pushed out of the hole; when you le…», reached through a sentence linked to the one the question matched. What matched: the same action «push in» (+4); the same thing acted on «outside air» (+3). · the question and its options parsed, with trees and pragmatics

Test 7 · ★★ · right ✓

Which shows warmth making air push harder?

1. A cold balloon growing back to full size as it warms — ← Mova's choice · ✓ the right answer · score 5
2. A tyre going flat from a nail — no support
3. Ketchup squirting out of a bottle when you squeeze it hard — no support
4. A sucker sticking to the tiles — no support

Why: It took the question to ask who or what does it. It chose option 1 with score 5, the only option with support. Its support: lesson 4, line 16: «A balloon let go without its knot squeezes air out of its neck, and the air rushing out pushes the balloon the other way.», reached through the same lesson line as the sentence the question matched. What matched: it fills the role the question asks for (+3); the same doer «balloon» (+2). · the question and its options parsed, with trees and pragmatics

Test 8 · ★★ · right ✓

In a cartoon a cook opens a pressure cooker the moment it stops hissing and smiles. What is the real rule?

1. Pressure cookers are never hot inside — no support
2. Only a grown-up opens it, after the pressure is safely let out — ← Mova's choice · ✓ the right answer · score 6
3. Anyone can open it whenever they like — score 4
4. You open it fastest by pulling hard on the lid — score 4

Why: It took the question to ask what it is done to. It chose option 2 with score 6, against 4 for the next best. Its support: lesson 16, line 12: «A fizzy drink has gas squashed into it under high pressure, and when you open it the pressure drops and the gas escapes as bubbles with a hiss; if the bottle w…», reached through the remembered sentence the question matched. What matched: it fills the role the question asks for (+6); the same thing acted on «pressure» (+4). Against it: a different action (counts against) (-2); a different doer (counts against) (-2). · the question and its options parsed, with trees and pragmatics

Test 9 · ★★ · right ✓

How is breathing in like pulling back the plunger of a syringe?

1. Neither depends on air pressure at all — no support
2. Both use a fan to move air — no support
3. Both work by making more room so the outside air pushes in — ← Mova's choice · ✓ the right answer · score 4
4. Both blow air out first so that they can pull more air back in — no support

Why: It took the question to ask what something is like. It chose option 3 with score 4, the only option with support. Its support: lesson 16, line 10: «Pulling back a syringe's plunger makes more room inside, the pressure drops, and the outside air pushes water in.», reached through the same lesson line as the sentence the question matched. What matched: the same action «push in» (+2); the same doer «outside air» (+2). · the question and its options parsed, with trees and pragmatics

Test 10 · ★★ · right ✓

You leave a hot jar of homemade jam to cool with the lid on tight. A day later the lid is pulled in. Why?

1. Someone squeezed it in the night — no support
2. The cooled air inside presses less than the air outside — ← Mova's choice · ✓ the right answer · score 5
3. The jam shrank and pulled the lid down by sticking to it — no support
4. The lid got cold and shrank more than the glass — no support

Why: It took the question to ask why something happens (its cause). It chose option 2 with score 5, the only option with support. Its support: lesson 14, line 2: «It presses from every side at once, up, down and sideways, on you, on the table and on the top of your juice.», reached through the option's own match among the sentences about the question's things. What matched: the same action «press» (+3); the same doer «air» (+2). · the question and its options parsed, with trees and pragmatics

Test 11 · ★★ · right ✓

Would a vacuum cleaner work on the Moon, with no air at all?

1. Yes, and it would work even better there than at home — no support
2. Only if you turned it right up to full power first — no support
3. No, there is no outside air to push the dust in — ← Mova's choice · ✓ the right answer · score 4
4. Yes, but it would only pick up the grey Moon dust — no support

Why: It took the question to ask which statement is true. It chose option 3 with score 4, the only option with support. Its support: lesson 16, line 15: «A balloon shrinks in the freezer and grows again when warmed, because cold air pushes less on the rubber.», reached through the remembered sentence the question matched. What matched: the same action «push» (+3); the same doer «cold air» (+1). · the question and its options parsed, with trees and pragmatics

Exam question 1 · formal language · wrong ✗

Identify the principal reason for which water boils at a reduced temperature at high altitude.

1. The vessel conducts heat less readily — no support
2. The atmospheric pressure acting upon the water is diminished — ✓ the right answer · score 3
3. The flame burns more fiercely in the thin air found at high altitude — ← Mova's choice · score 4
4. The water is of a different chemical composition — no support

Why: It took the question to ask which statement is true. It chose option 3 with score 4, against 3 for the next best. Its support: lesson 13, line 1: «The deeper you go in water, the harder it presses, because more and more water is piled up above you; you feel it in your ears at the bottom of a deep pool.», reached through the option's own match among the sentences about the question's things. What matched: the same action «feel» (+2); the same thing acted on «water» (+2). The right option, 2, scored 3. · the question and its options parsed, with trees and pragmatics

Exam question 2 · formal language · wrong ✗

Which of the following statements most accurately characterises the operation of a vacuum cleaner?

1. The dust is attracted by a magnetic field within the device — ← Mova's choice · no support
2. The nozzle adheres to the dust chemically — no support
3. The external air, at higher pressure, propels the dust into a region of reduced pressure — ✓ the right answer · no support
4. The dust is rendered lighter than the surrounding air — no support

Why: No option found support in what it remembers, so it guessed: it took the first option shown. · the question and its options parsed, with trees and pragmatics

Exam question 3 · formal language · wrong ✗

It is given that the volume of the chest cavity is enlarged during inhalation. Determine the immediate consequence.

1. The pressure within the lungs increases and air is expelled — ← Mova's choice · no support
2. The heart propels air into the lungs — no support
3. No movement of air occurs — no support
4. The pressure within the lungs diminishes and external air enters — ✓ the right answer · no support

Why: No option found support in what it remembers, so it guessed: it took the first option shown. · the question and its options parsed, with trees and pragmatics

Exam question 4 · formal language · wrong ✗

State the reason for which a pressure cooker is fitted with a safety valve.

1. The valve cools the steam to below boiling — ← Mova's choice · no support
2. Excessive pressure of confined steam would constitute a hazard — ✓ the right answer · no support
3. The valve serves solely to release the odours of the food being cooked — no support
4. The valve permits the food to be observed — no support

Why: No option found support in what it remembers, so it guessed: it took the first option shown. · the question and its options parsed, with trees and pragmatics

This page in Markdown → https://md.mova.elamur.ai/free/en/school-run/physics/16-pressure-tricks-pumps-tyres-vacuums/