In order to make the effective acceleration due to gravity equal to zero at the equator, the angular velocity of rotation of the earth about its axis should be

In order to make the effective acceleration due to gravity equal to zero at the equator, the angular velocity of rotation of the earth about its axis should be  (g= 10 ms^-2  and radius of earth is 6400 kms)

(a) 0 rad sec^-1                       (b)    1/800 rad sec^-1

(c)  1/80 rad sec^-1                       (d)  1/8 rad sec^-1

Answer: b