An atomic nucleus at rest decays radioactively into an alpha particle and a nucleus smaller than the original. What will be the speed of this recoiling nucleus if the speed of the alpha particle is 1.20E+05 m/s? Assume the recoiling nucleus has a mass 56 times as great as that of the alpha particle.

Answer 1

momentum=zero
Malpha*1.20E05=Malpha*56*v
solve for v.