[填空题]
What is the linear s:sow. ledf1s 8(0iga imi7u9hpeed of 6v ax:jg.h 9dw06f sy rp ;wa82weg)pra 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? $m/s$