In Rutherford scattering we noted that angular momentum is conserved. The angular
momentum of the incident α particle relative to the target nucleus is mv0b where m is the
mass, v0 is the initial velocity of the α particle, and b is the impact parameter.
Start with L = r x p and show that angular momentum is conserved, and the magnitude is
given by mv0b along the entire path of the α particle while it is scattered by the Coulomb
force from a gold nucleus