---
title: Identify the principal reason for which a person standing upon a ska… — Pushes and pulls: what makes things mo… · tree and pragmatics
description: Identify the principal reason for which a person standing upon a skateboard moves backwards upon throwing a heavy ball forwards. Exam question 3 of lesson 4 «Pushes and pulls: what makes things move and stop» of the physics course of Mova's primary school, with the dependency tree and pragmatics of 
---

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# Exam question 3 · Pushes and pulls: what makes things move and stop

<!-- .ven lang=en -->
Identify the principal reason for which a person standing upon a skateboard moves backwards upon throwing a heavy ball forwards.

<!-- .vintro -->
**Mova's choice:** option 1 · **The right answer:** option 3 · wrong ✗ · **Who acts:** you, person · **What happens:** identify, stand, move, throw · **To what, where:** principal reason, skateboard, heavy ball

<!-- .vabout -->
This is exam question 3 of lesson 4 «Pushes and pulls: what makes things move and stop» of the physics course of Mova's primary school, asked in stiff, formal language. The page gives the question's syntax tree — a dependency tree in the style of Universal Dependencies — and its pragmatics clause by clause, then the 4 options as the student saw them, each with its tree and pragmatics. Every text is parsed by Mova itself. How the student answered it, with the score of every option and why: [the test at school](https://md.mova.elamur.ai/free/en/school-run/physics/4-pushes-and-pulls-move-and-stop/#e3).

## The question {#question}

```conllu
# sent_id = question:physics:4-pushes-and-pulls-move-and-stop:e3:1
# text = Identify the principal reason for which a person standing upon a skateboard moves backwards upon throwing a heavy ball forwards.
1	Identify	identify	VERB	VB	Mood=Imp|VerbForm=Fin	0	root	_	_
2	the	the	DET	DT	Definite=Def|PronType=Art	4	det	_	_
3	principal	principal	ADJ	JJ	Degree=Pos	4	amod	_	_
4	reason	reason	NOUN	NN	Number=Sing	1	obj	_	_
5	for	for	ADP	IN	_	6	case	_	_
6	which	which	PRON	WDT	PronType=Rel	13	obl	_	_
7	a	a	DET	DT	Definite=Ind|PronType=Art	8	det	_	_
8	person	person	NOUN	NN	Number=Sing	13	nsubj	_	_
9	standing	stand	VERB	VBG	VerbForm=Ger	8	acl	_	_
10	upon	upon	ADP	IN	_	12	case	_	_
11	a	a	DET	DT	Definite=Ind|PronType=Art	12	det	_	_
12	skateboard	skateboard	NOUN	NN	Number=Sing	9	obl	_	_
13	moves	move	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	4	acl	_	_
14	backwards	backwards	ADV	RB	_	13	advmod	_	_
15	upon	upon	SCONJ	IN	_	16	mark	_	_
16	throwing	throw	VERB	VBG	Tense=Pres|VerbForm=Part	13	advcl	_	_
17	a	a	DET	DT	Definite=Ind|PronType=Art	19	det	_	_
18	heavy	heavy	ADJ	JJ	Degree=Pos	19	amod	_	_
19	ball	ball	NOUN	NN	Number=Sing	16	obj	_	_
20	forwards	forwards	ADV	RB	_	16	advmod	_	SpaceAfter=No
21	.	.	PUNCT	.	_	1	punct	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **identify** | imperative | you *not said here* | the principal reason |  |  |  |  | vn characterize-29.2-1-1 «NP V NP S\_ING»: agent=Agent reason=Theme |
| 2 | **stand** | gerund | a person *not said here* |  |  | a skateboard |  |  | vn assuming\_position-50 «NP V PP.location»: agent=Agent upon skateboard=Location |
| 3 | **move** | present | a person |  |  |  |  | for the principal reason; backwards *property* | vn roll-51.3.1 «NP.theme V»: agent=Theme |
| 4 | **throw** | gerund | a person *not said here* | a heavy ball |  |  |  | forwards *property* | vn throw-17.1-1-1 «NP V NP»: agent=Agent ball=Theme |

<!-- .note -->
One row per clause the reader finds. «not said here»: a role filled from the clause above. «roles by»: a VerbNet class and frame when one fits the verb, else the reader's rules on the tree.

## The options {#options}

### Option 1 · ← Mova's choice {#o1}

<!-- .ven lang=en -->
The ground exerts a horizontal force towards the rear

```conllu
# sent_id = question:physics:4-pushes-and-pulls-move-and-stop:e3:o1:1
# text = The ground exerts a horizontal force towards the rear
1	The	the	DET	DT	Definite=Def|PronType=Art	2	det	_	_
2	ground	ground	NOUN	NN	Number=Sing	3	nsubj	_	_
3	exerts	exert	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	0	root	_	_
4	a	a	DET	DT	Definite=Ind|PronType=Art	6	det	_	_
5	horizontal	horizontal	ADJ	JJ	Degree=Pos	6	amod	_	_
6	force	force	NOUN	NN	Number=Sing	3	obj	_	_
7	towards	towards	ADP	IN	_	9	case	_	_
8	the	the	DET	DT	Definite=Def|PronType=Art	9	det	_	_
9	rear	rear	NOUN	NN	Number=Sing	3	obl	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **exert** | present | the ground | a horizontal force |  |  |  | towards the rear | vn use-105.1 «NP V NP»: agent=Agent force=Theme |

### Option 2 {#o2}

<!-- .ven lang=en -->
The air in front of the person is compressed

```conllu
# sent_id = question:physics:4-pushes-and-pulls-move-and-stop:e3:o2:1
# text = The air in front of the person is compressed
1	The	the	DET	DT	Definite=Def|PronType=Art	2	det	_	_
2	air	air	NOUN	NN	Number=Sing	9	nsubj:pass	_	_
3	in	in	ADP	IN	_	4	case	_	_
4	front	front	NOUN	NN	Number=Sing	2	nmod	_	_
5	of	of	ADP	IN	_	7	case	_	_
6	the	the	DET	DT	Definite=Def|PronType=Art	7	det	_	_
7	person	person	NOUN	NN	Number=Sing	4	nmod	_	_
8	is	be	AUX	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	9	aux:pass	_	_
9	compressed	compress	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	0	root	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **compress** | present · passive |  | the air in front of the person |  |  |  |  | vn bend-45.2 «NP V NP.patient»: subject=Patient |

### Option 3 · ✓ the right answer {#o3}

<!-- .ven lang=en -->
The ball exerts upon the person a force equal and opposite to that applied

```conllu
# sent_id = question:physics:4-pushes-and-pulls-move-and-stop:e3:o3:1
# text = The ball exerts upon the person a force equal and opposite to that applied
1	The	the	DET	DT	Definite=Def|PronType=Art	2	det	_	_
2	ball	ball	NOUN	NN	Number=Sing	3	nsubj	_	_
3	exerts	exert	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	0	root	_	_
4	upon	upon	ADP	IN	_	6	case	_	_
5	the	the	DET	DT	Definite=Def|PronType=Art	6	det	_	_
6	person	person	NOUN	NN	Number=Sing	3	obl	_	_
7	a	a	DET	DT	Definite=Ind|PronType=Art	8	det	_	_
8	force	force	NOUN	NN	Number=Sing	3	obj	_	_
9	equal	equal	ADJ	JJ	Degree=Pos	14	advcl	_	_
10	and	and	CCONJ	CC	_	11	cc	_	_
11	opposite	opposite	ADJ	JJ	Degree=Pos	9	conj	_	_
12	to	to	ADP	IN	_	13	case	_	_
13	that	that	PRON	DT	Number=Sing|PronType=Dem	11	obl	_	_
14	applied	apply	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	3	parataxis	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **exert** | present | the ball | a force |  |  |  | upon the person | vn use-105.1 «NP V NP»: agent=Agent force=Theme |
| 2 | **apply** | participle |  |  |  |  |  |  | vn use-105.1 «NP V NP»: agent=Agent |

### Option 4 {#o4}

<!-- .ven lang=en -->
The skateboard possesses a motion of its own

```conllu
# sent_id = question:physics:4-pushes-and-pulls-move-and-stop:e3:o4:1
# text = The skateboard possesses a motion of its own
1	The	the	DET	DT	Definite=Def|PronType=Art	2	det	_	_
2	skateboard	skateboard	NOUN	NN	Number=Sing	3	nsubj	_	_
3	possesses	possess	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	0	root	_	_
4	a	a	DET	DT	Definite=Ind|PronType=Art	5	det	_	_
5	motion	motion	NOUN	NN	Number=Sing	3	obj	_	_
6	of	of	ADP	IN	_	8	case	_	_
7	its	its	PRON	PRP$	Case=Gen|Gender=Neut|Number=Sing|Person=3|Poss=Yes|PronType=Prs	8	nmod:poss	_	_
8	own	own	ADJ	JJ	Degree=Pos	5	nmod	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **possess** | present | the skateboard | a motion of skateboard's own |  |  |  |  | vn own-100.1 «NP V NP»: agent=Pivot motion=Theme |

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**Text:** the tests of Mova's primary school, written for Mova (`world/data/school/`), as the course runner gave them to the student. **Trees:** Mova's own parse — the `en` model on the CPU, when the site is built — not checked by a teacher; they may be wrong. **Frames:** Mova's frames reader (`prag`), each text read on its own. Elamur Cosmic License.

<!-- /div -->

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- ← previous: [Pushes and pulls: what makes things mo…, exam 2](https://md.mova.elamur.ai/free/en/corpora/questions/physics/4-pushes-and-pulls-move-and-stop/e2/)
- next →: [Pushes and pulls: what makes things mo…, exam 4](https://md.mova.elamur.ai/free/en/corpora/questions/physics/4-pushes-and-pulls-move-and-stop/e4/)
- ↑ back to [Pushes and pulls: what makes things move and stop](https://md.mova.elamur.ai/free/en/corpora/questions/physics/4-pushes-and-pulls-move-and-stop/)