Two objects of equal mass collide on a horizontal frictionless surface. Before the collision, object A is at rest while object B has a constant velocity of 12 m/s. After the collision, the two objects are stuck together. What is the speed of the composite body (A +B) after the collision?
A)3.0 m/s
B)6.0 m/s
C)12 m/s
D)24 m/s
E)36 m/s

Question

Quizplus · Accepted Answer

The law of conservation of momentum states that the total momentum before the collision is equal to the total momentum after the collision. Before the collision, only object B has momentum, which is mass * velocity = m * 12 m/s. After the collision, the combined mass is 2m, and the velocity is v. Setting the initial and final momentum equal: m * 12 = 2m * v, solving for v gives v = 6 m/s.

Two Objects of Equal Mass Collide on a Horizontal Frictionless