Three particles A, B and C of equal mass move with equal speed v along the medians of an equilateral triangle as shown in figure. They collide at the centroid G of the triangle. After the collision, A comes to rest, B retraces its path with the speed v. What is the velocity of C ?

Question

Three particles A, B and C of equal mass move with equal speed v along the medians of an equilateral triangle as shown in figure. They collide at the centroid G of the triangle. After the collision, A comes to rest, B retraces its path with the speed v. What is the velocity of C ? (A)  (B)  (C)  (D)

Tardigrade Admin · Accepted Answer

Before collision net momentum of the system was zero.
No external force is acting on the system. Hence, momentum after collision should also be zero.

A

has come to rest. Therefore,

B

and

C

should have equal and opposite momenta or velocity of

C

should be

v

in opposite direction of velocity of

B

.

Q. Three particles A,B and C of equal mass move with equal speed v along the medians of an equilateral triangle as shown in figure. They collide at the centroid G of the triangle. After the collision, A comes to rest, B retraces its path with the speed v. What is the velocity of C ?

Before collision net momentum of the system was zero. No external force is acting on the system. Hence, momentum after collision should also be zero. A has come to rest. Therefore, B and C should have equal and opposite momenta or velocity of C should be v in opposite direction of velocity of B.