The earth has a radius of 6380 km and turns around once on its axis in 24 h. If arad at the equator is greater than g, objects will fly off the earth’s surface and into space. What would the period of the earth’s rotation have to be for this to occur?
选项：

A:5070 S ;
B:8060 S ;
C:3.4 h;
D:6080 S;
E:4.6 h ;
F:1.4h