this post was submitted on 28 Aug 2024
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[–] SpaceNoodle@lemmy.world 68 points 2 months ago* (last edited 2 months ago) (2 children)

They're traveling away from their origin at constant velocities, so they're traveling relative to each other at constant velocities as well.

The magnitude of the resulting vector (i.e., speed) can be calculated trivially since their movement is perpendicular on a plane, as the root of sum of squares, which many could recognize as the Pythagorean theorem:

√((5 ft/s)² + (1 ft/s)²) = √26 ft/s ≈ 5.1 ft/s

You can verify this by finding that their average speed apart is the same at all times (for all t > 0):

Vavg = √((t * 5 ft/s)² + (t * 1 ft/s)²) / t = √(t² * ((5 ft/s)² + (1 ft/s)²)) / t = √26 ft/s

[–] key@lemmy.keychat.org 24 points 2 months ago* (last edited 2 months ago) (1 children)

Don't forget to calculate the location where everything about them began and then include the curvature of Earth considering the latitude of said location into your speed calculation.

[–] SpaceNoodle@lemmy.world 33 points 2 months ago (3 children)

No, they're spherical children in a vacuum.

[–] answersplease77@lemmy.world 13 points 2 months ago

for approximation we can assume that the boy is a point mass and the girl is a lie

[–] ICastFist@programming.dev 5 points 2 months ago

Oh, so we have to calculate the gravitational attraction pulling them back. Fucking hell

[–] Hamartia@lemmy.world 2 points 2 months ago

Augustus! Save some room for later.

[–] Randelung@lemmy.world 3 points 2 months ago* (last edited 2 months ago) (1 children)

https://en.m.wikipedia.org/wiki/Spherical_geometry

I couldn't find 'potatoy geometry' for a better approximation of earth.

[–] SpaceNoodle@lemmy.world 1 points 2 months ago (1 children)

You'll note that I already assumed that they were on a plane, not the surface of a sphere.

[–] Randelung@lemmy.world -1 points 2 months ago (1 children)

I'm also noting the stick up your ass. 🙄

If the potato remark and subreddit don't tip you off that I was being flippant, I don't know what will.

[–] SpaceNoodle@lemmy.world 2 points 2 months ago

No, the stick would be a one-dimensional line.