[填空题]
What is the linear speedcuql :dv+am)9u7q/ v yw ma;)h2obs v8a ;uqf( of a poinyvm8e0e ig :q3t (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? $m/s$