Using Newton's law of gravitation, calculate density of earth.

Explanation

If p is uniform density of earth taken as a perfect sphere, then `M=(4)/(3)piR^(3) p`
As `g=GM//R^(2) , M=gR^(2)//G`
`:. p=(3M)/(4piR^(3))=(3gR^(2))/(G.4piR^(3))=(3g)/(4piGR)=(3xx9.8)/(4xx22/7xx6.67xx10^(-11)xx6.4xx10^(6))=5.48xx10^(3) kg//m^(3)`.