posted by kate on .
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
5 × 106 m/s, what would be the recoil speed
of the thorium nucleus?
Answer in units of m/s
m1 = 6.64•10^−27 kg , v1 =5•10^6 m/s,
m2 = 3.88•10^-25 kg, v2 = ?
0 = m1•v1 – m1•v2,
v2 = m1•v1/v2 =
= 6.64•10^-27•5•10^6/3.88•10^-25 =
= 8.56•10^4 m/s.