A uranium nucleus 238U may stay in one piece for billions of years, but sooner or later it decays into an a 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 a particle is emitted at a speed of 1.07×107 m/s, what would be the recoil speed of the thorium nucleus?

Question

A uranium nucleus 238U may stay in one piece for billions of years, but sooner or later it decays into an a 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 a particle is emitted at a speed of 1.07×107 m/s, what would be the recoil speed of the thorium nucleus? 
Answer in units of m/s.

I got -183113.4021m/s, but that was wrong, and so was 183113.4021m/s

bobpursley · Answer

Massparticle*velocityParticle=massU234*V solve for V. 6.46E-27*1.07E7=3.88E-25*V I agree, your answers are not correct.