Two blocks M1 and M2 having equal mass are to move on a horizontal frictionless surface. M2 is attached to a massless spring as shown in figure. Initially M2 is at rest and M1 is moving toward M2 with speed v and collides head-on with M2.

Question

Two blocks M1 and M2 having equal mass are to move on a horizontal frictionless surface. M2 is attached to a massless spring as shown in figure. Initially 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

Tardigrade Admin · Accepted Answer

While spring is fully compressed, the entire KE of M1 is not stored as PE of spring as M2 may move. If spring is massless, than as M1=M2, velocities of M1 and M2 are interchanged on collision. M1 comes to rest, instead of M2. Choice (c) is correct. If surface on which blocks are moving has friction loss of energy is involved . Collision cannot be elastic. Choice (d) is correct.

Q. Two blocks $M_{1}$ and $M_{2}$ having equal mass are to move on a horizontal frictionless surface. $M_{2}$ is attached to a massless spring as shown in figure. Initially $M_{2}$ is at rest and $M_{1}$ is moving toward $M_{2}$ with speed $v$ and collides head-on with $M_{2}$ .

While spring is fully compressed all the KE of $M_{1}$ is stored as PE of spring

While spring is fully compressed the system momentum is not conserved though final momentum is equal to initial momentum

If spring is massless, the final state of the $M_{1}$ is state of rest

If the surface on which blocks are moving has friction, then collision cannot be elastic

Q. Two blocks M1​ and M2​ having equal mass are to move on a horizontal frictionless surface. M2​ is attached to a massless spring as shown in figure. Initially M2​ is at rest and M1​ is moving toward M2​ with speed v and collides head-on with M2​.

While spring is fully compressed all the KE of M1​ is stored as PE of spring

While spring is fully compressed the system momentum is not conserved though final momentum is equal to initial momentum

If spring is massless, the final state of the M1​ is state of rest

If the surface on which blocks are moving has friction, then collision cannot be elastic

Q. Two blocks $M_{1}$ and $M_{2}$ having equal mass are to move on a horizontal frictionless surface. $M_{2}$ is attached to a massless spring as shown in figure. Initially $M_{2}$ is at rest and $M_{1}$ is moving toward $M_{2}$ with speed $v$ and collides head-on with $M_{2}$ .

While spring is fully compressed all the KE of $M_{1}$ is stored as PE of spring

If spring is massless, the final state of the $M_{1}$ is state of rest