Living with friction: oil, wheels and grip
Tests: 5 of 10 right · Exam: 1 of 4 right · Kind: ★ · Understood: 6 of 14 · Run: 2026-10-18, commit f3c23ea72
Lesson 7 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 ✗
What would a day with no friction at all be like?
- 1. Nothing would ever move — ← Mova's choice · no support
- 2. You could not walk, hold a pencil or tie your shoes — ✓ the right answer · no support
- 3. Things would only fall upwards — no support
- 4. Everything would be easier to hold — no support
Why: It could not read the question into a frame, so it guessed: it took the first option shown. · the question and its options parsed, with trees and pragmatics
Test 2 · ★ · wrong ✗
argh this jar won't open, any tips??
- 1. Shake it hard while holding it upside down — ← Mova's choice · no support
- 2. Oil the whole lid all over so it slides — no support
- 3. Put it in the freezer for an hour first — no support
- 4. Use a rubber glove or warm the lid — ✓ 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 3 · ★ · wrong ✗
My mate says a spacecraft glows only cos it rubs on the air. right?
- 1. Yes, it is only rubbing — ← Mova's choice · no support
- 2. No, the Sun heats it up — no support
- 3. No, its engines are what make it glow so brightly — no support
- 4. Mostly the squeezed air in front heats up — ✓ 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 4 · ★ · wrong ✗
Why would a gymnast with sweaty hands be in danger on the bars?
- 1. Sweat freezes onto the cold metal bars at once — ← Mova's choice · no support
- 2. Sweat makes the bar bend — no support
- 3. Sweaty skin is slippery and she could slip — ✓ the right answer · no support
- 4. Sweat makes her too heavy — 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 · ★ · right ✓
In a cartoon a cat slides across the kitchen on a banana skin. Why is a banana skin slippery?
- 1. The banana skin bounces you up into the air — no support
- 2. Bananas are lighter than air — no support
- 3. Bananas are always magnetic — no support
- 4. It puts a slippery layer under your foot — ← Mova's choice · ✓ the right answer · score 5
Why: It took the question to ask why something happens (its cause). It chose option 4 with score 5, the only option with support. Its support: lesson 7, line 19: «A banana skin is slippery because its squashed inside makes a slimy layer between your shoe and the floor.», reached through the cause of the sentence the question matched. What matched: the same thing acted on «slimy layer» (+5). · the question and its options parsed, with trees and pragmatics
Test 6 · ★ · wrong ✗
You must move a heavy fridge across a room. Which helps most?
- 1. Push it hard from the top corner — ← Mova's choice · score 2
- 2. Put it on a trolley with wheels — ✓ the right answer · no support
- 3. Push it much faster at the start — no support
- 4. Put a thick heavy rug on top of it — no support
Why: It took the question to ask who or what does it. It chose option 1 with score 2, the only option with support. Its support: lesson 4, line 4: «Forces come in pairs: stand on a skateboard and throw a heavy ball forward, and the ball pushes you backwards just as hard.», reached through the option's own match among the sentences about the question's things. What matched: the same action «push» (+2); the same property (+1). Against it: a different doer (counts against) (-1). The right option, 2, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics
Test 7 · ★ · right ✓
Why does a fisherman wet his hands before holding a fish?
- 1. So the fish stays heavier — no support
- 2. So the fish is easier to grip — no support
- 3. So he does not rub off the slime that protects it — ← Mova's choice · ✓ the right answer · score 6
- 4. Because dry hands are too cold — no support
Why: It took the question to ask why something happens (its cause). It chose option 3 with score 6, the only option with support. Its support: lesson 7, line 15: «Fish are slippery because their skin is covered in slime, which also protects them from germs, so wet your hands before holding one.», reached through the same lesson line as the sentence the question matched. What matched: the same action «protect» (+3); the same doer «slime» (+3). · the question and its options parsed, with trees and pragmatics
Test 8 · ★ · right ✓
What would happen to a car engine with no oil?
- 1. It would use less petrol — no support
- 2. Its parts would rub, overheat and seize — ← Mova's choice · ✓ the right answer · score 5
- 3. Nothing at all — no support
- 4. It would go faster — no support
Why: It took the question to ask which statement is true. It chose option 2 with score 5, the only option with support. Its support: lesson 7, line 6: «Car engines need oil; without it their metal parts would rub, heat up and seize (jam solid).», reached through the remembered sentence the question matched. What matched: the same action «rub» (+3); the same doer «metal parts» (+2). · the question and its options parsed, with trees and pragmatics
Test 9 · ★ · right ✓
wheels spinning and screaming, what should the driver do?
- 1. Press the pedal down even harder to get away quicker — no support
- 2. Put the brakes on and off — no support
- 3. Start more smoothly so the tyres roll and grip — ← Mova's choice · ✓ the right answer · score 8
- 4. Turn the steering wheel quickly — no support
Why: It took the question to ask what is done. It chose option 3 with score 8, the only option with support. Its support: lesson 7, line 7: «Wheels roll instead of rub, so a suitcase on wheels moves easily, and before wheels people rolled huge stones on logs.», reached through the remembered sentence the question matched. What matched: it fills the role the question asks for (+6); the same action «roll» (+4). Against it: a different doer (counts against) (-2). · the question and its options parsed, with trees and pragmatics
Test 10 · ★ · right ✓
Why do skateboards spin for ages but an old cart wheel creaks to a stop?
- 1. Ball bearings roll instead of rub — ← Mova's choice · ✓ the right answer · score 4
- 2. Skateboards are pulled less by gravity — no support
- 3. Old wood has no friction at all — no support
- 4. Cart wheels are heavier than skates — no support
Why: It took the question to ask why something happens (its cause). It chose option 1 with score 4, the only option with support. Its support: lesson 7, line 7: «Wheels roll instead of rub, so a suitcase on wheels moves easily, and before wheels people rolled huge stones on logs.», reached through the option's own match among the sentences about the question's things. What matched: the same action «roll» (+3); the same circumstance (+2). Against it: a different doer (counts against) (-1). · 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 function of lubricating oil in a hinge?
- 1. It interposes a slippery layer between the metal surfaces — ← Mova's choice · ✓ the right answer · no support
- 2. It increases the mass of the moving parts — no support
- 3. It attracts the parts towards one another — no support
- 4. It renders the metal soft and pliable — 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 ✗
Identify the principal advantage of a wheel over a sledge for the conveyance of heavy loads.
- 1. Sliding occasions less friction than rolling — ← Mova's choice · no support
- 2. A wheel eliminates the effect of gravity — no support
- 3. Rolling occasions far less friction than sliding — ✓ the right answer · no support
- 4. A wheel diminishes the weight of the load considerably — 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 3 · formal language · wrong ✗
It is given that two books are interleaved page by page. Ascertain the reason for which they resist separation.
- 1. The books exert a magnetic attraction — ← Mova's choice · no support
- 2. The pages are united by an adhesive — no support
- 3. The friction of numerous pages is cumulatively very great — ✓ the right answer · no support
- 4. The air between the pages is removed entirely — 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 ✗
Determine the consequence for ordinary human activity of the total absence of friction.
- 1. All bodies would remain permanently at rest upon the ground — ← Mova's choice · no support
- 2. Walking would be rendered effortless — no support
- 3. Objects would adhere to the hands — no support
- 4. Walking and grasping objects would be impossible — ✓ 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
This page in Markdown → https://md.mova.elamur.ai/free/en/school-run/physics/7-living-with-friction/