Answer:
v = 10 [m/s].
Step-by-step explanation:
The largest mass is that of 4 [kg], in this way the momentum can be calculated by means of the product of the mass by velocity.
where:
P = momentum [kg*m/s]
m = mass = 4 [kg]
v = velocity = 5 [m/s]
Now the momentum:
This same momentum is equal for the other mass, in this way we can find the velocity.