The radius of the earth is \(6400\ km\) and \(g=10 {ms}^{-2}\). In order that the body of \(5\ kg\) weighs zero at the equator, the angular speed of the earth should be:
1
\(\dfrac {1}{80}{rads}^{-1}\)
2
\(\dfrac {1}{400}{rads}^{-1}\)
3
\(\dfrac {1}{800}{rads}^{-1}\)
4
\(\dfrac {1}{1600}{rads}^{-1}\)