While riding bumper cars at the fair, bob's car collides directly with the back of joe's car while both cars are moving to the right. before the collision, joe's car was traveling at 1.8 m/s and bob's car at 2.0m/s. the combined mass of joe and his car is only 80 kg, and the combined mass of bob and his car is 100 kg. immediately after the collision, joe's car moves right at 2.0 m/s. how fast and in which direction does bob's car move?