Question

a cue ball strikes an 8 ball of equal mass, which is initailly at rest. the cue ball stops and the 8 ball moves forward with a velocity equal to the intial velocity of cue ball. is the collsiion elastic

Answer 1

The collision is elastic:

In all elastic collisions of that type (unidirectional) the velocity of approach equals the velocity of separation - the collision is elastic even for different masses

e = relative velocity after / relative velocity before

e = 1 for elastic collisions