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)
g′=g−ω2Rcos2λ
For weightlessness at equator λ=0 and g′=0
∴0=g−ω2R⇒w=√gR=1800rads