Auranium nucleus 238u may stay in one piece for billions of years, but sooner or later it decays into an α particle of mass 6.64×10−27 kg and 234th nucleus of mass 3.88 × 10−25 kg, and the decay process itself is extremely fast (it takes about 10−20 s). suppose the uranium nucleus was at rest just before the decay. if the α particle is emitted at a speed of 6.31×106 m/s, what would be the recoil speed of the thorium nucleus? answer in units of m/s