[填空题]
What is the linear spekqx);(l wwq3v l jyq-t4e3 t1fe+/z 9rozjyh v4je 5lz,d of 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? $m/s$