Calculate angular velocity of the earth so that acceleration due to gravity at `60^(@)` latitude becomes zero (radius of the earth = 6400 km, gravitational acceleration at poles = `10 m//s^(2) , cos60^(@) = 0.5`)
A. `(GMm)/(11R)`
B. `(GMm)/(10R)`
C. `(mgR)/(11G)`
D. `(10GMm)/(11R)`