Question

what would be the value of g on the surface of Earth if its mass was twice and its radius half of what it is now​

Answer 1

g=GM/R^2 if the mass is doubled that is M'=2M and radius is half of previous then R'=R/2 therefore R'^2=R^2/4

By dividing the new result of g with previous i.e.

g'/g = 8

Therefore the new g on the earths surface will be 8 times of previous one

Answer 2

Answer:

g= Gm÷r^2. So when given situation is taken then g=G 2m ÷(r^2÷4) = g= 2×4(Gm÷r^2) = g=8(Gm÷r^2). So value of g becomes 8 times in the given situation.