In a hypothetical world on a planet where r = 12x10^6 and G is the same as ever, how do I calculate mass and acceleration due to gravity? thanks :)
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Determine g by g = V^2/2H where V is a measured impact speed and H is the height something is dropped from. Then you can do g = GM/r^2 and M = gr^2/G, where G is G and r = 12E6 m.
If you're doing this from afar and the planet has a moon, you can find g = (2pi/T)^2 R where T is the moon's period and R is its radius of orbit, both of which are observable from afar. And then, as before, M = gR^2/G with the g field based on the moon's data.
If you're doing this from afar and the planet has a moon, you can find g = (2pi/T)^2 R where T is the moon's period and R is its radius of orbit, both of which are observable from afar. And then, as before, M = gR^2/G with the g field based on the moon's data.
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Yep g is too big. I suspect your semi major axis will need modification so that an average circular orbit results. I think you'll need to invoke Kepler's equal sweeps of area to put the elliptical orbit into an equivalent circular one
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Drop an object and measure how long it takes to fall. If the mass is the same as Earth's, the acceleration would be about 0.29 times as much.
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If that's really all the info given, you're out of luck........