Given data
*The given mass of the train car is m = 2600 kg
*The initial speed of the train is u = 10 m/s
*The second mass of the train car is M = 2500 kg
*The initial speed of the second train car is v = 0 m/s
The formula for the final velocity of the two train cars is given as

Substitute the values in the above expression as

Thus, the final velocity of the two train cars is V = 5.09 m/s