Bangs and loud sounds: firecrackers and ears
Tests: 4 of 11 right · Exam: 3 of 4 right · Kind: ★ · Understood: 7 of 15 · Run: 2026-10-18, commit f3c23ea72
Lesson 19 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 · ★ · right ✓
my bro says a dud firework is safe to pick up after a minute. right?
- 1. Yes, after a minute it is dead — no support
- 2. No, but after five minutes it is safe — no support
- 3. Yes, if you pour a little water on it first, it is completely dead — no support
- 4. No, it can still go off later, leave it and tell an adult — ← Mova's choice · ✓ the right answer · score 4
Why: It took the question to ask which statement is true. It chose option 4 with score 4, the only option with support. Its support: lesson 19, line 10: «A firework that did not go off can still explode later, so you never go back to a lit firework; you leave it and tell an adult.», reached through the same lesson line as the sentence the question matched. What matched: the same action «tell» (+2); the same receiver «adult» (+2). · the question and its options parsed, with trees and pragmatics
Test 2 · ★ · right ✓
mate held a banger in his hand for a laugh in a video. what's the real danger?
- 1. It just makes your hand tingle for a bit — no support
- 2. None, bangers are only loud — no support
- 3. It can break bones, burn skin and take off fingers — ← Mova's choice · ✓ the right answer · score 5
- 4. It only hurts if the banger is wet or old, otherwise it is fine — no support
Why: It took the question to ask which statement is true. It chose option 3 with score 5, the only option with support. Its support: lesson 19, line 3: «Close up, that slam is strong enough to hurt: it hits your eardrum with a sudden hard push, and in someone's hand the hot gas can break bones and burn skin, wh…», reached through the remembered sentence the question matched. What matched: the same action «break» (+3); the same thing acted on «bones» (+3). Against it: a different doer (counts against) (-1). · the question and its options parsed, with trees and pragmatics
Test 3 · ★ · wrong ✗
What would happen if a firecracker burst far away across a field instead of next to you?
- 1. It would be silent, because sound cannot cross fields — ← Mova's choice · score 4
- 2. It would be just as loud as close up — score 4
- 3. It would be louder, because sound grows with distance — score 4
- 4. The bang would be much weaker by the time it reached you — ✓ the right answer · no support
Why: It took the question to ask what happens next. It chose option 1 with score 4, tied with another option at 4 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 19, line 9: «A firecracker going off in a hand can break bones and burn flesh, and every year hospitals treat children who lost fingers to fireworks.», reached through what followed the sentence the question matched. What matched: the same doer «firecracker» (+4). The right option, 4, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics
Test 4 · ★ · wrong ✗
In a cartoon a firecracker goes off in a cat's paws and the cat just has sooty fur. What is wrong?
- 1. Real fireworks only ever burn your hair and never your skin — ← Mova's choice · no support
- 2. Real cats are immune to bangs — no support
- 3. Nothing, that is exactly what happens — no support
- 4. Real fireworks can badly injure anyone who holds them — ✓ 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
Test 5 · ★ · wrong ✗
Why is a balloon pop like a tiny firecracker bang?
- 1. Both are made of the same powder — ← Mova's choice · no support
- 2. Both are lit with a match — no support
- 3. Both bang because of the light they make — no support
- 4. Both are squashed gas escaping all at once in one sharp wave — ✓ 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
Test 6 · ★ · wrong ✗
Bloody neighbours with their fireworks again, my dog's shaking under the bed. What helps?
- 1. Let him run loose in the garden — score 8
- 2. Take him outside so he gets used to it and calms down — ← Mova's choice · score 10
- 3. Shout at him to stop shaking — no support
- 4. Keep him in, curtains shut, some quiet music on — ✓ the right answer · no support
Why: It took the question to ask who or what does it. It chose option 2 with score 10, against 8 for the next best. Its support: lesson 17, line 15: «Dogs can hear much higher notes than people can, and people hear the highest notes less and less as they grow older.», reached through the remembered sentence the question matched. What matched: it fills the role the question asks for (+6); the same doer «dogs» (+4). The right option, 4, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics
Test 7 · ★ · right ✓
Why is ringing in the ears after a concert or a bang not something to laugh off?
- 1. It warns of damage to hair cells that never grow back — ← Mova's choice · ✓ the right answer · no support
- 2. It means your ears are getting tougher — no support
- 3. It always goes away by the morning, so it means nothing at all — no support
- 4. It is just your brain humming the song — 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 8 · ★ · wrong ✗
Which is true about how sound weakens?
- 1. It gets louder and louder the further it travels from the bang — ← Mova's choice · score 4
- 2. It spreads out over a bigger area the further it goes — ✓ the right answer · score 4
- 3. It stops completely after it has travelled one kilometre or so — score 3
- 4. It weakens only at night, when the air is cold and heavy — no support
Why: It took the question to ask which statement is true. It chose option 1 with score 4, tied with another option at 4 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 18, line 3: «Sound moves much faster through solid things like steel or a tight string than through air, because their tightly packed bits pass the wobble on quickly.», reached through the remembered sentence the question matched. What matched: the same action «move» (+3); the same doer «sound» (+1). The right option, 2, scored 4. · the question and its options parsed, with trees and pragmatics
Test 9 · ★ · wrong ✗
A new rubber strip is stuck on the door frame. What will change?
- 1. The door will not close properly at all any more — ← Mova's choice · no support
- 2. The door will close with a quieter thud — ✓ the right answer · no support
- 3. The door will swing open on its own in a draught — no support
- 4. The door will bang even louder than before — 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 10 · ★ · wrong ✗
A friend says noise-cancelling headphones work by just being very thick. What is the cleverer truth?
- 1. They suck the sound away into a little box inside them — ← Mova's choice · no support
- 2. They play the opposite wave to cancel the noise — ✓ the right answer · no support
- 3. They turn the noise into light that you cannot see — no support
- 4. They are very thick and soft, and nothing more than that — 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 11 · ★ · right ✓
A film crew crunches celery for the sound of a breaking bone. Why does it work?
- 1. Celery and bones are made of the same stuff — no support
- 2. The audience cannot hear the difference between any two sounds at all — no support
- 3. Our brains recognise the pattern of the wobbles, not the object — ← Mova's choice · ✓ the right answer · score 10
- 4. The microphone changes every sound into bones — no support
Why: It took the question to ask why something happens (its cause). It chose option 3 with score 10, the only option with support. Its support: lesson 19, line 18: «Sound effects copy real sounds with other things, such as coconut shells for horses' hooves, because our brains recognise the pattern of the wobbles.», reached through the cause of the sentence the question matched. What matched: the same thing acted on «pattern» (+5); the same action «recognise» (+3); the same doer «brains» (+2). · the question and its options parsed, with trees and pragmatics
Exam question 1 · formal language · right ✓
Identify the principal mechanism by which a firecracker produces its report.
- 1. The emission of intense light — no support
- 2. The rupture of the paper casing alone — no support
- 3. The rapid conversion of its charge into hot gas, which displaces the air in a single pressure wave — ← Mova's choice · ✓ the right answer · score 2
- 4. The vibration of a metallic component within the casing — no support
Why: It took the question to ask which statement is true. It chose option 3 with score 2, the only option with support. Its support: lesson 19, line 6: «A firecracker bangs because the powder inside burns in a flash, making a lot of hot gas that shoves the air outwards in one sharp pressure wave.», reached through the same lesson line as the sentence the question matched. What matched: the same thing acted on «air» (+2); the same place «one sharp pressure wave» (+2). Against it: a different action (counts against) (-1); a different doer (counts against) (-1). · the question and its options parsed, with trees and pragmatics
Exam question 2 · formal language · right ✓
Which of the following statements most accurately characterises the appropriate conduct in respect of a firework that has failed to ignite?
- 1. It is not to be approached, and an adult is to be informed — ← Mova's choice · ✓ the right answer · no support
- 2. It is to be relit forthwith — no support
- 3. It may safely be handled if dampened — no support
- 4. It may be retrieved after a brief interval of a minute or thereabouts — 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 ✗
State the consequence of acoustic injury to the sensory hair cells of the inner ear.
- 1. No consequence ensues — ← Mova's choice · no support
- 2. The cells are strengthened by the exposure — no support
- 3. The cells are not regenerated and the damage is permanent — ✓ the right answer · no support
- 4. The cells regenerate entirely within the space of about a week — no support
Why: Nothing it remembers matched the question, so it guessed: it took the first option shown. · the question and its options parsed, with trees and pragmatics
Exam question 4 · formal language · right ✓
Ascertain the principle by which noise-cancelling headphones reduce ambient noise.
- 1. A wave opposite to the incident noise is generated so that the two cancel — ← Mova's choice · ✓ the right answer · no support
- 2. The noise is absorbed by foam exclusively — no support
- 3. The noise is masked by music of greater volume — no support
- 4. The noise is converted into light — 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/19-bangs-and-loud-sounds-firecrackers-and-ears/