-. A 2kg cart moving to the right at 5m/s collides with an 8kg cart at rest. As a result of the collision, the cart locks together. What is the velocity of the carts
after the event?

The velocity of the carts after the event is 1 m/s

Explanation:

Law Of Conservation Of Linear Momentum

The total momentum of a system of bodies is conserved unless an external force is applied to it. The formula for the momentum of a body with mass m and speed v is  

P=mv.  

If we have a system of bodies, then the total momentum is the sum of the individual momentums:

If a collision occurs and the velocities change to v', the final momentum is:

Since the total momentum is conserved, then:

P = P'

In a system of two masses, the equation simplifies to:

If both masses stick together after the collision at a common speed v', then:

The common velocity after this situation is:

The m1=2 kg cart is moving to the right at v1=5 m/s. It collides with an m2= 8 kg cart at rest (v2=0). Knowing they stick together after the collision, the common speed is:

The velocity of the carts after the event is 1 m/s