PhysicsLAB: June 2017, Part 1
11. A 7.0kilogram cart, A, and a 3.0kilogram cart, B, are initially held together at rest on a horizontal, frictionless surface. When a compressed spring attached to one of the carts is released, the carts are pushed apart. After the spring is released, the speed of cart B is 6.0 meters per second, as represented in the diagram below.