[填空题]
An atomic nucleus inijs)hy 3v)q koy nv td6s ryss);v:(a**tially moving at 420m/s emits an :2 a-zlf wwlz9*pf:krblf 68u alpha particle in the direction of its velocity, and the remaining nucleus slows to 350m/s If the alpha particle has a mass of 4.0 u and the original 6 ub:w82a*:lwrfll fz -z9pfknucleus has a mass of 222 u, what speed does the alpha particle have when it is emitted? m/s