32. IE ••• A particle of mass m, initially moving at speed v, collides head on elastically with an identical particle initially at rest.

(a) Do you expect the total mass of the two particles after the collision to be

(1) greater than 2m, (2) equal to 2m, or (3) less than 2m? Why?

(b) What are the total energy and momentum of the two particles after the collision, in terms of m, v, and c?