Question

An alpha particle of momentum p is bombarded on the nucleus the distance of closest approach is r if the momentum of the alpha particle is made six times the distance of closest approach becomes

Answer 1

assume that when the alpha particle has momentum 'p', it is far enough from the nucleus so that its potential energy can be considered to be zero. kinetic energy= p2/2m, at closest approach kinetic energy=0, and potential energy=p2/2m=k/r, where k is a constant which can easily be obtained from elementary electrostatics. r=2mk/p2, thus r is inversely proportional to p2,
Therefore, if momentum of alpha particle is made 6 times, distance of closest approach becomes r/36