Two blocks M1 and M2 having equal mass are free to move on a horizontal frictionless surface. M2 is attached to a massless spring as shown in Fig. 6.10. Iniially M2 is at rest and M1 is moving toward M2 with speed v and collides head-on with M2.
(a) While spring is fully compressed all the KE of M1 is stored as PE of spring.
(b) While spring is fully compressed the system momentum is not conserved, though final momentum is equal to initial momentum.
(c) If spring is massless, the final state of the M1 is state of rest.
(d) If the surface on which blocks are moving has friction, then collision cannot be elastic.