Randall D. Knight — Impulse and Momentum: Problem 68

The nucleus of the polonium isotope \(^{214}\text{Po}\) (mass \(214\text{ u}\)) is radioactive and decays by emitting an alpha particle (a helium nucleus with mass \(4\text{ u}\)). Laboratory experiments measure the speed of the alpha particle to be \(1.92 \times 10^7\text{ m/s}\). Assuming the polonium nucleus was initially at rest, what is the recoil speed of the nucleus that remains after the decay?