[填空题]
What is the linear spee :bcu,c;jyi +lhqh(qr 7*0s x3qd(ubpd*r* a cyfr*l42 zb,1 ylfctmv9 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? $m/s$