[填空题]
What is the linear speed gri2 0uig:ugg5c q.5vooj(6m oet1byc /5nf* f)tk0 gc3;awbff a point (a) on the equator, $m/s$ (b) on the Arctic Circle (latitude 66.5$^{\circ} $ N), $m/s$ (c) at a latitude of 45.0$^{\circ} $ N, due to the Earth’s rotation? $m/s$