[填空题]
What is the linear spebf) ;wf4b-2 s ,ebvwtin,wjy )ed of4-jr1;kq8ye. kl q cca 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? $m/s$