1. The problem statement, all variables and given/known data Two identical blocks of the same mass travel at velocities of 3v and 2v on a smooth surface as shown (same direction). Two blocks move together after collision. What is their common velocity? 2. Relevant equations Conservation of momentum 3. The attempt at a solution Let v' be the common velocity. 3mv+2mv = 2mv' v'= 2.5v Therefore the veloctiy is 2.5v. Answer given is 1.5v.