Question

If the earth suddenly stops rotating about its axis what would be the effect on the value of g ?

Answer 1

if the earth stops rotating, the value of acceleration due to gravity will be equal to 9.832...It's the centrifugal force, which is effecting g.

Answer 2

there will be no change in g.
..SINCE g'= g -R w^2 cos^2 (lambda)..where w is the angular velocity of the earth
and if the earth stops rotating then. w=0
u will get g'=g