The blue bumper car 100 kg is moving 10 m/s to the East and collides with a red bumper car 100 kg moving 4 m/s to the West. They stick together after the collision. What is their final velocity?

Aball with a mass of 275 g is dropped from rest, hits the floor and rebounds upward. if the ball hits the floor with a speed of 2.40 m/s and rebounds with a speed of 1.70 m/s, determine the following. (a) magnitude of the change in the ball's momentum (let up be in the positive direction.)