On a frictionless surface, a 2-kilogram cart moves at a velocity of 3 meters per second west and hits a 4-kilogram cart that is not moving, initially. The two carts stick together and move off at a slower speed to the west. What is this slower speed?


a. 0. 5 meters/second


b. 1 meter/second


c. 1. 5 meters/second


d. 2 meters/second