The three freight cars are rolling along the horizontal trac

The three freight cars are rolling along the horizontal track with the velocities shown. After the impacts occur, the three cars become coupled together and move with a common velocity v. The weights of the loaded cars A, B and C are 130,000, 100,000 and 150,000 lb, respectively. Determine v.

Solution

momentum conservation of the system

m1u1 + m2u2 + m3u3 = (m1+m2+m3)*v

=> 130000*2 + 1*100000 - 1.5*150000 = ( 130000+100000+150000)*v

=> v = 0.355 mile/hr