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The planet's surface gravity is not 8 g. Surface gravity goes like mass over radius squared, and the planet's radius is 2.6 times Earth's, so the surface gravit
by pdonis 3y ago
The planet's surface gravity is not 8 g. Surface gravity goes like mass over radius squared, and the planet's radius is 2.6 times Earth's, so the surface gravity will be 8 / (2.6)^2, or only about 1.2 times that of Earth.
- adolph 3y agoThat is if density remains constant. If the planet were 8x mass but with same radius, gravity would be 8 g, or 8 × 9.795 m/s^s. Earth mass: 5.97×10^24 kg, 6378.137 km yields 9.795 m/s^2 8x mass: (8×5.97)×10^24 kg, 6378.137 km yields 78.36 m/s^2 All calculations: https://www.wolframalpha.com/input?i=surface+gravity+calculator https://www.wolframalpha.com/input?i=surface+gravity+calcula...
- pdonis 3y ago> That is if density remains constant. No, the calculation I made did not assume constant density. I just used the direct Newtonian formula for surface gravity and plugged in the known mass and radius of the planet. (You could also use that known mass and radius to calculate the average density. But you don't need to do that to calculate the surface gravity.) > If the planet were 8x mass but with same radius But we know it isn't. We know the planet's radius is 2.6 times the Earth's radius. That's stated in the article.
- mr_toad 3y ago> If the planet were 8x mass but with same radius That’s not possible for normal stable matter. The Earth’s density is about 5g per cubic centimetre. Iron is 7.8g per cubic centimetre. Osmium is the densest stable element at 22.6g per cubic centimetre.
- thot_experiment 3y agoJuuuuusssttt barely below the limit to be able to launch chemical rockets into space (IIRC it's ~1.3g)
- rayrey 3y agoLol. Seeing that response and then your username