In a head on collision between two particles, is it necessary that the two particles will acquire the same/common velocity for at least one instant?
Bonus question : Same question but now one of the particles is rear ending the second one.
Extra Info : It is not mentioned if the collision is elastic, semi elastic or inelastic. So I think that we need to cover all three cases.
What I'm thinking : I think that their velocities will indeed be zero (for both) for an instant.. because only then can the direction of velocity reverse. But what I'm not clear on is if they will have zero velocity at the SAME instant.
BOOK : Concepts of Physics volume 1 by H.C. Verma (Indian book). Page 156 question 8.