system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can we calculate the mass of the earth?
gpt
We start with the formulas
>Weight = m*g

and
>F_g = GMm/R^2

which is just Newton's second law and Newton's law of universal gravitation. If we equate the two, we get
>M=gR^2 /G

so if we know the gravitational acceleration on the surface of Earth, radius of Earth and the gravitational constant G we can calculate the mass of Earth easily.