Answer:
The velocity of cart B after the collision is 1.29 m/s.
Step-by-step explanation:
We can find the velocity of cart B by conservation of linear momentum:


Where:
is the mass of cart A = 600 g = 0.6 kg
is the mass of cart B = 200 g = 0.2 kg
is the inital velocity of cart A = 0.7 m/s
is the final velocity of cart A = 0.27 m/s
is the initial velocity of cart B = 0
is the final velocity of cart B =?
Taking the left direction as the positive horizontal direction:


Therefore, the velocity of cart B after the collision is 1.29 m/s.
I hope it helps you!