if mass and radius of earth becomes four times than the value of g becomes
Answers
Answer:
G is a universal constant and will never change
Small g is the force that gravity exerts on the surface of the Earth. If just the mass changes, then the gravitational pull would be 4 times more. But if the Earth increased in radius as well, it's more complicated.
F ~ M/r^2 force is proportional to mass/radius squared.
g = m/r^2. Gravity is in g is equal to earth masses/earth radius^2.
By increasing mass, we proportionally increase volume (assuming constant density). This means that 4 Earth would have a radius that is cube root 4 bigger than Earth.
So due to the mass, the gravity increases by a factor of 4. But due to the new radius, it would decrease by a factor (cube root 4)^2, or 4^(2/3).
Rearrange this to get your new gravity as (cube root 4)g.