A uranium nucleus 238U may stay in one piece
for billions of years, but sooner or later it de-
cays into an 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 particle is emitted at a speed of
9.58×106 m/s, what would be the recoil speed
of the thorium nucleus?
Answer in units of m/s

Question

A uranium nucleus 238U may stay in one piece
for billions of years, but sooner or later it de-
cays into an  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  particle is emitted at a speed of
9.58×106 m/s, what would be the recoil speed
of the thorium nucleus?
Answer in units of m/s

anonymous · Answer

m1v1=m2v2

anonymous · Answer

I have the speed of the uranium?

anonymous · Answer

no...of particle ...take it v1

anonymous · Answer

law of conservation of momentum is applicable here

anonymous · Answer

I was trying to figure out what velocity I pair up to what mass

jfraser · Answer

the uranium mass isn't actually important, because you know that the 2 pieces after the decya each have a mass and each have a velocity. All that's missing is the velocity of the thorium