Pulleys, gears and big machines

Tests: 4 of 11 right · Exam: 0 of 4 right · Kind: ★★ · Understood: 8 of 15 · Run: 2026-10-18, commit f3c23ea72

Lesson 35 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, the car's on the jack, just crawl under and grab my ball. fine?

1. Yes, if you are quick — ← Mova's choice · no support
2. Yes, if the engine is off — no support
3. No, never go under a car held only by a jack; it can slip — ✓ the right answer · no support
4. Yes, jacks never fail — 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 · ★★ · wrong ✗

A builder hooks his rope through four pulleys instead of one. Why does he have to pull so much rope?

1. He is pulling the wrong end — ← Mova's choice · score 7
2. The extra pulleys make the rope stretchy — no support
3. Four pulleys make the load heavier, so he needs more rope — score 4
4. Less force means pulling over a longer distance — ✓ the right answer · no support

Why: It took the question to ask why something happens (its cause). It chose option 1 with score 7, against 4 for the next best. Its support: lesson 35, line 2: «Thread a rope through several pulleys and the load hangs on many lengths of rope that share its weight, so a builder pulls with much less force, but must pull…», reached through the same lesson line as the sentence the question matched. What matched: the same action «pull» (+5); the same doer «builder» (+2). The right option, 4, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 3 · ★★ · wrong ✗

In a cartoon, a crane lifts a whole ship far out on its arm with no counterweight and stays perfectly upright. What's wrong?

1. Cranes can lift anything at all — no support
2. A real crane would tip over without balance — ✓ the right answer · score -2
3. Ships are lighter than air — ← Mova's choice · score 6
4. Nothing, a real crane never tips over whatever it lifts — score 1

Why: It took the question to ask which statement is true. It chose option 3 with score 6, against 1 for the next best. Its support: lesson 11, line 11: «A steel ship floats because it is hollow and full of air, so the water it moves aside weighs more than the ship; squashed into a lump, it would sink.», reached through the option's own match among the sentences about the question's things. What matched: the same doer «ship» (+3); the same circumstance (+2); the same light verb (be, have, do, get, go) (+1). The right option, 2, scored -2. · the question and its options parsed, with trees and pragmatics

Test 4 · ★★ · right ✓

your mum says lifts can fall like in films. should you panic?

1. No, lifts float on air — no support
2. No, lifts have several cables and safety brakes — ← Mova's choice · ✓ the right answer · score 8
3. Yes, they hang on only one thin cable that can snap — no support
4. Yes, lifts fall all the time — score 7

Why: It took the question to ask which statement is true. It chose option 2 with score 8, against 7 for the next best. Its support: lesson 35, line 12: «A lift is pulled up by cables over a wheel, with a counterweight going down as it goes up; lifts have several cables and safety brakes, so falling is almost im…», reached through the option's own match among the sentences about the question's things. What matched: the same thing acted on «several cables» (+4); the same doer «lifts» (+3); the same light verb (be, have, do, get, go) (+1). · the question and its options parsed, with trees and pragmatics

Test 5 · ★★ · wrong ✗

Jas is cycling up a steep hill and her legs are dying. What should she do?

1. Pump up her tyres — ← Mova's choice · no support
2. Change to an easier gear — ✓ the right answer · no support
3. Change to the hardest gear — no support
4. Stop pedalling and coast — 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 ✗

Three gears are in a row. The first turns clockwise. Which way does the third turn?

1. Clockwise — ✓ the right answer · no support
2. It turns both ways at once — ← Mova's choice · score 11
3. It does not turn — no support
4. Anticlockwise — no support

Why: It took the question to ask what it is done to. It chose option 2 with score 11, the only option with support. Its support: lesson 35, line 11: «Two meshing gears always turn in opposite directions, and a third gear in between makes the last one turn the same way as the first.», reached through the remembered sentence the question matched. What matched: it fills the role the question asks for (+6); the same thing acted on «same way» (+4); the same action «turn» (+3). Against it: a different doer (counts against) (-2). The right option, 1, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 7 · ★★ · right ✓

What would happen if a clock's hour hand were joined straight to the minute hand with no gears?

1. The clock would run backwards instead of forwards — no support
2. The clock would chime every few minutes all day — no support
3. Both hands would turn at the same speed — ← Mova's choice · ✓ the right answer · score 2
4. The hour hand would stop and never move again — score 2

Why: It took the question to ask what happens next. It chose option 3 with score 2, tied with another option at 2 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 6, line 4: «Rub your hands together on a cold day and they warm up: friction always turns some movement into heat.», reached through what followed the sentence the question matched. What matched: the same doer «hands» (+4). Against it: a different action (counts against) (-2). · the question and its options parsed, with trees and pragmatics

Test 8 · ★★ · wrong ✗

Why did villagers long ago build their mill next to a stream?

1. Flour must be washed after grinding — ← Mova's choice · no support
2. The miller needed water to drink — no support
3. Flowing water turned the wheel that ground the flour — ✓ the right answer · no support
4. Streams keep millstones cold — 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 9 · ★★ · right ✓

What's the clever trick that lets one motor run a whole escalator?

1. Magnets lift each step — no support
2. A long loop of steps is pulled round by a motor and gears — ← Mova's choice · ✓ the right answer · score 2
3. Each step has its own small engine — no support
4. People's weight pushes the steps up — no support

Why: It took the question to ask which statement is true. It chose option 2 with score 2, the only option with support. Its support: lesson 35, line 10: «Gears in a clock let one motor turn the minute hand twelve times round for each single turn of the hour hand.», reached through the option's own match among the sentences about the question's things. What matched: the same doer «one motor» (+3). Against it: a different action (counts against) (-1). · the question and its options parsed, with trees and pragmatics

Test 10 · ★★ · wrong ✗

Why can you raise the school flag with one hand even though the flag is high up?

1. The pulley lets you pull down to lift it up — ✓ the right answer · no support
2. The rope is magnetic and slides up the metal pole — no support
3. The pole stretches upwards when you pull the rope — ← Mova's choice · score 4
4. The flag is pulled up high by the wind on its own — no support

Why: It took the question to ask why something happens (its cause). It chose option 3 with score 4, the only option with support. Its support: lesson 35, line 7: «With several pulleys, more lengths of rope share the load, so you pull with less force but must pull much more rope.», reached through the option's own match among the sentences about the question's things. What matched: the same action «pull» (+3); the same thing acted on «more rope» (+1). The right option, 1, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 11 · ★★ · right ✓

Why can a small motor raise a heavy lift full of people?

1. The counterweight balances most of the weight — ← Mova's choice · ✓ the right answer · no support
2. The cables pull upward on their own without any motor — no support
3. The lift is filled with helium — no support
4. People weigh less in lifts — 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 1 · formal language · wrong ✗

Identify the principal function of a single fixed pulley.

1. To increase the energy which is available to the operator — ← Mova's choice · no support
2. To reduce the mass of the load — no support
3. To prevent the rope from stretching — no support
4. To alter the direction in which a force is applied — ✓ 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 2 · formal language · wrong ✗

Ascertain the direction of rotation of a gear meshed directly with a second gear rotating clockwise.

1. It alternates in direction — ← Mova's choice · no support
2. It remains stationary — no support
3. Anticlockwise — ✓ the right answer · no support
4. Clockwise — 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 ✗

Which of the following statements most accurately characterises the purpose of the counterweight of a lift?

1. It prevents the car from ascending beyond the uppermost floor — ← Mova's choice · no support
2. It secures the doors in a closed position — no support
3. It is held in reserve against the failure of the car — no support
4. It balances the car so that the motor need raise only the difference in weight — ✓ 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 ✗

Select the response consistent with the established facts concerning a system of several pulleys.

1. The effort is diminished, but a greater length of rope must be drawn — ✓ the right answer · no support
2. The load is rendered lighter in itself — no support
3. Both the effort and the rope drawn are diminished — ← Mova's choice · score 8
4. The effort is increased, but less rope need be drawn — no support

Why: It took the question to ask which statement is true. It chose option 3 with score 8, the only option with support. Its support: lesson 35, line 7: «With several pulleys, more lengths of rope share the load, so you pull with less force but must pull much more rope.», reached through the option's own match among the sentences about the question's things. What matched: the same action «pull» (+4); the same thing acted on «more rope» (+4). The right option, 1, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

This page in Markdown → https://md.mova.elamur.ai/free/en/school-run/physics/35-pulleys-gears-and-big-machines/