13. When using direct quotations, one rule to follow is to
use correct grammar and avoid slang.
use the level of formality or informality that would be natural for the speaker.
quote people generally using words such as "everyone" or "someone"
instead of using their names.
group quotations into a single paragraph within a dialogue between two or
more people.

this answer was editing it cause i couldn't delete!

the author motivation is to show the power of animal-human relationships.

the boy's acceleration toward the girl is 2.08 m/s^2.

explanation:

according the newton's third law, the force causing the girl accelerate towards the boy will be me with equal counter-force causing the boy to accelerate towards the girl. these forces will be of equal magnitude and allows us to determine the boy's acceleration:

the boy's acceleration toward the girl is 2.08 m/s^2.