[填空题]
What is the linear speed of a p c kyky a96/: yhg,0p.xmsim;xhcwp-2 tlk0y,4mysrimn;, e 0oint (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? $m/s$