Question

An astronomical object has its mass 4 times the mass of earth and radius half of the radius of earth if acceleration due to gravity at Earth is g find its value at the surface of the astronomical objects

Answer 1

M= 4m
R=r/2
g=Gm/r*r
g'=(G*4m)/(r/2)(r/2)
g'=( G*4m*4)/(r*r)
g'=16Gm/r*r
Hence g'= 16g
g'=16*10
=160 metre per second square.
Thanks.....