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Is the gravity pull of the Earth negligible at 50 miles up, or is the weightlessness experience just relative to a falling airframe?

https://en.wikipedia.org/wiki/Reduced-gravity_aircraft

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  • $\begingroup$ Gravitational acceleration toward the Earth is about 97.5% of Earth surface gravitation at an altitude of 50 miles. I'm positive this is a duplicate; this question has been asked many, many times before. $\endgroup$ Jul 14, 2021 at 4:06

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Is the gravity pull of the Earth negligible at 50 miles up...

No it's almost the same. Gravitational acceleration varies as

$$a = \frac{GM_{Earth}}{r^2}$$

Let's call 50 miles 80 km. Earth's equatorial radius is about 6378 km, so gravity at 80 km is

$$\left(\frac{6378}{6378+80}\right)^2 \approx 97.5\text{% of Earth.}$$

...or is the weightlessness experience just relative to a falling airframe?

You guessed it! They both just rise and fall at the same rate, so the "weightlessness experience" is just that, an experience no different than jumping off of a stool, except that it's longer because they jumped higher.

I'll add a link to Q&A here that address this in greater detail if/when I can find them. I'm pretty sure this has been explained in the context of the astronauts aboard the ISS; they're both "falling" or oribing the Earth, and up there gravity is about 85.5% that of the surface.

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