Forces — pushes, pulls, friction and magnets

Tests: 6 of 13 right · Exam: 1 of 4 right · Kind: plain · Understood: 10 of 17 · Run: 2026-10-18, commit f3c23ea72

Lesson 51 of the world 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 ✗

A cyclist stops pedalling on a flat road. Why does the bicycle slowly stop?

1. The road attracts it like a magnet — ← Mova's choice · no support
2. The bicycle runs out of energy inside it — no support
3. Gravity pulls it backwards along the road — no support
4. Friction and air resistance slow it down — ✓ 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 2 · wrong ✗

Why do football boots have studs on the sole?

1. To stop gravity pulling the player down — ← Mova's choice · no support
2. To make the boots lighter to run in — no support
3. To reduce friction so the players can slide — no support
4. To grip the ground and increase friction — ✓ the right answer · 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

Test 3 · wrong ✗

Two magnets lie on a table and slide away from each other when brought close. What must be facing each other?

1. Nothing, magnets always move apart — no support
2. A pole and the middle of the other magnet — score 4
3. A north pole and a south pole — ← Mova's choice · score 6
4. Two like poles, such as south and south — ✓ the right answer · score 4

Why: It took the question to ask what it is done to. It chose option 3 with score 6, against 4 for the next best. Its support: lesson 51, line 14: «Every magnet has a north pole and a south pole.», reached through the remembered sentence the question matched. What matched: it fills the role the question asks for (+3); the same property (+2); the same thing acted on «north pole» (+1). The right option, 4, scored 4. · the question and its options parsed, with trees and pragmatics

Test 4 · wrong ✗

You have a mixture of iron nails and sand. What is the easiest way to separate them?

1. Blow on it with a fan — no support
2. Pull the nails out with a magnet — ✓ the right answer · no support
3. Shake the mixture in a jar — score 2
4. Pour water over the mixture — ← Mova's choice · score 7

Why: It took the question to ask what it is done to. It chose option 4 with score 7, against 2 for the next best. Its support: lesson 27, line 3: «A camel stores fat (not water) in its hump, can go many days without drinking, has wide feet for soft sand and can close its nostrils against blowing sand; a c…», reached through the same lesson line as the sentence the question matched. What matched: it fills the role the question asks for (+4); the same thing acted on «fat» (+3). The right option, 2, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 5 · right ✓

Which is true about friction?

1. It is the same thing as gravity — score 4
2. It only exists between surfaces made of metal — no support
3. It always helps things move faster — score 6
4. It works against movement and makes heat — ← Mova's choice · ✓ the right answer · score 7

Why: It took the question to ask which statement is true. It chose option 4 with score 7, against 6 for the next best. Its support: lesson 51, line 3: «Friction is a force that appears when two surfaces rub against each other. It always works against the movement, so it slows things down and turns some of the…», reached through a sentence linked to the one the question matched. What matched: the same action «work» (+3); the same doer «friction» (+2); the same circumstance (+2). · the question and its options parsed, with trees and pragmatics

Test 6 · right ✓

Why do people put oil on a squeaky bicycle chain?

1. Oil increases the grip of the chain — no support
2. Oil makes the metal magnetic — no support
3. Oil makes the chain heavier and stronger — no support
4. Oil reduces the friction between the moving parts — ← Mova's choice · ✓ the right answer · score 2

Why: It took the question to ask why something happens (its cause). It chose option 4 with score 2, the only option with support. Its support: lesson 51, line 11: «Oil and water on a surface reduce friction, which is why wet floors are slippery.», reached through the option's own match among the sentences about the question's things. What matched: the same action «reduce» (+3). Against it: the same doer «oil» (-1). · the question and its options parsed, with trees and pragmatics

Test 7 · right ✓

You squeeze a lump of clay and it becomes flat. What did the force do?

1. It made the clay lighter than air — score 12
2. It made the clay magnetic — score 12
3. It changed the shape of the clay — ← Mova's choice · ✓ the right answer · score 18
4. It changed the weight of the clay — score 14

Why: It took the question to ask what is done. It chose option 3 with score 18, against 14 for the next best. Its support: lesson 51, line 1: «A force is a push or a pull. Forces can start something moving, stop it, speed it up, slow it down, turn it or change its shape.», reached through the remembered sentence the question matched. What matched: it fills the role the question asks for (+6); the same action «change» (+4); the same doer «forces» (+4); the same thing acted on «shape» (+4). · the question and its options parsed, with trees and pragmatics

Test 8 · wrong ✗

If there were no friction at all, what would happen when you tried to walk?

1. You would float up into the air — ← Mova's choice · no support
2. Your feet would slip and you could not move forward — ✓ the right answer · no support
3. You would walk much faster than before, without effort — no support
4. Nothing would change at all — 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 · wrong ✗

Which of these does a magnet NOT attract?

1. An iron nail — ← Mova's choice · score 1
2. A steel spoon — score 1
3. A nickel washer — score 1
4. A gold ring — ✓ the right answer · score 1

Why: It took the question to ask what it is done to. It chose option 1 with score 1, tied with another option at 1 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 51, line 5: «Gravity is the pull of the Earth that makes things fall and gives them weight. Magnets pull on iron and steel, and they can pull or push other magnets without…», reached through the option's own match among the sentences about the question's things. What matched: the same action «pull» (+2); the same doer «magnets» (+2). Against it: one says «not», the other does not (counts against) (-3). The right option, 4, scored 1. · the question and its options parsed, with trees and pragmatics

Test 10 · right ✓

why's the floor so slippy after mopping

1. Water reduces friction between your shoes and the floor — ← Mova's choice · ✓ the right answer · no support
2. Wet floors pull you down harder — no support
3. The water pushes your feet away — no support
4. The mop makes the floor magnetic — 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

Test 11 · wrong ✗

tried to stick a magnet on a coke can, didnt work, why

1. Magnets only stick to wood — ← Mova's choice · no support
2. Aluminium is not magnetic — ✓ the right answer · no support
3. The magnet was upside down — no support
4. The can was too 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 12 · right ✓

my brother says heavy things fall cos the air pushes them down. true?

1. No, gravity, the pull of the Earth, makes them fall — ← Mova's choice · ✓ the right answer · score 10
2. Yes, without air nothing would fall — no support
3. No, things fall because they are heavy inside — score 6
4. Yes, air pushes down on everything — score 3

Why: It took the question to ask which statement is true. It chose option 1 with score 10, against 6 for the next best. Its support: lesson 51, line 5: «Gravity is the pull of the Earth that makes things fall and gives them weight. Magnets pull on iron and steel, and they can pull or push other magnets without…», reached through the same lesson line as the sentence the question matched. What matched: the same action «make» (+4); the same doer «pull» (+4); the same thing acted on «things» (+2). · the question and its options parsed, with trees and pragmatics

Test 13 · right ✓

Mia reckons two north poles of magnets stick together. right?

1. Yes, but only big magnets — no support
2. No, magnets never push apart — no support
3. No, like poles repel; opposite poles attract — ← Mova's choice · ✓ the right answer · score 6
4. Yes, the same poles always attract each other — score 6

Why: It took the question to ask which statement is true. It chose option 3 with score 6, tied with another option at 6 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 51, line 15: «Opposite poles of two magnets attract and like poles repel.», reached through the remembered sentence the question matched. What matched: the same action «repel» (+4); the same doer «opposite poles» (+2). · the question and its options parsed, with trees and pragmatics

Exam question 1 · formal language · right ✓

Which of the following statements most accurately characterises the phenomenon designated as friction?

1. A force arising between surfaces in contact which invariably opposes their relative motion — ← Mova's choice · ✓ the right answer · score 5
2. A force arising between surfaces in contact which invariably assists their relative motion — score 5
3. A force exerted solely by magnetised bodies upon ferrous materials — no support
4. A force by which the Earth draws all bodies towards its centre — no support

Why: It took the question to ask who or what does it. It chose option 1 with score 5, tied with another option at 5 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 51, line 3: «Friction is a force that appears when two surfaces rub against each other. It always works against the movement, so it slows things down and turns some of the…», reached through the same lesson line as the sentence the question matched. What matched: it fills the role the question asks for (+4); the same doer «force» (+3). Against it: a different action (counts against) (-2). · the question and its options parsed, with trees and pragmatics

Exam question 2 · formal language · wrong ✗

It is given that a sledge is propelled with equal force across ice and across grass. Identify the principal reason for its greater displacement upon the ice.

1. The ice exerts an attractive force upon the runners of the sledge — ← Mova's choice · no support
2. The gravitational pull of the Earth is diminished above ice — no support
3. The smoothness of the ice occasions a lesser frictional resistance — ✓ the right answer · no support
4. The mass of the sledge is reduced whilst upon a frozen surface — 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 ✗

Select the response that is consistent with the established facts concerning the interaction of two magnets whose like poles are placed in proximity.

1. The magnets shall repel one another — ✓ the right answer · no support
2. The magnets shall attract one another — ← Mova's choice · score 2
3. The magnets shall be wholly unaffected by one another — no support
4. The magnets shall forfeit their magnetic properties — 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 51, line 5: «Gravity is the pull of the Earth that makes things fall and gives them weight. Magnets pull on iron and steel, and they can pull or push other magnets without…», reached through the option's own match among the sentences about the question's things. What matched: the same action «pull» (+1); the same doer «magnets» (+1). The right option, 1, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Exam question 4 · formal language · wrong ✗

Whereas a magnet is applied in turn to the objects hereinafter enumerated, determine which object shall be attracted thereto.

1. A receptacle of aluminium — ← Mova's choice · no support
2. A ring of gold — no support
3. A fastening of steel — ✓ the right answer · no support
4. A coin of copper — 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

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