Question

The distance of closest approach of an alpha particle reaching a nucleus with momentum p is r.when the alpha particle travel towards the same nucleus with momentum p/2, the distance of closest approach Wil be

Answer 1

Initial momentum P= mv, where m= mass of the alpha particle and

v= velocity with which it travels towards the nucleus.

The closest path to approach nucleus is r, if the alpha particle is moving with momentum P.

We also know, P=mv= m(r/t)

If the particle is moving momentum P/2= (mv)/2= m(v/2)= m(r/2t)

Since mass is constant. So definitely speed will be halved. Thus the closest approach would be r/2