[填空题]
What is the linear sxr/2n v .+ na+oopn6jnr:k(g jd7 s-30gnzhdvg 37xs 4i rb)f9 mnvi-bpeed 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? $m/s$