Question

how the mass of the earth was calculated without knowing gravity

Answer 1

The mass of the Earth may bedetermined using Newton's law ofgravitation. ... We know that the acceleration due to gravity is equal to 9.8 m/s2, the Gravitational constant (G) is 6.673 × 10−11 Nm2/kg2, the radius of the Earth is 6.37 × 106 m, andmass cancels out.

Answer 2

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There is another way to measure the mass—a method that doesn't rely on the gravitational field. That means you can use this balance on Earth, or Mars, or even in deep space where the is no gravity (yes, there is gravity in low Earth orbit)

$\large\rm\fcolorbox{black}{lightgreen}{Hope \: it \: helps \: you}$