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FlyJunior172 t1_iugqqcj wrote

The numbers you’re hearing are linear speed, not angular speed.

vᵣ=rω where v is the linear speed, r is the radius of rotation and ω is the angular speed.

For earth, r = 3950 mi, and ω = 15°/h. This gives vᵣ= 3950×15×π÷180=1034.107666 mi/h (π÷180 is just a unit conversion) at the equator. Sound familiar?

Now, what really matters is ω - that 15°/h. This is half the angular speed of the hour hand on a clock. The hour hand on a clock goes around twice in a day, which works out to 30°/h. That’s not a movement we can easily perceive when viewed from altitudes like the one the Blue Marble photo was taken at, the perspective we have of the earth is very similar to the perspective we have of a clock. The angular speed is just slow enough we can’t perceive it.

Edit: unit errors in my math

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ShesOver9k OP t1_iugx80s wrote

>vᵣ=rω where v is the linear speed, r is the radius of rotation and ω is the angular speed.

>For earth, r = 3950 mi, and ω = 15°/h. This gives vᵣ= 3950×15×π÷180=1034.107666 mi/h (π÷180 is just a unit conversion) at the equator. Sound familiar?

That is not explaining like I'm 5 lol, but actually a really good answer, ty.

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FlyJunior172 t1_iugy3pt wrote

I wish there were a simpler way to explain where the big number comes from, but unfortunately there isn’t.

All the other methods I’ve learned for dealing with spinning things involve far more complicated math - usually matrices and reference frame conversions. This would be more of an ELI20, where v=rω is more like ELI8.

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