Q1: (20 marks) A 9,300 kg Railroad car traveling at a velocity of 15m/s strikes a second boxcar at rest. If the two cars stick together and move off with a velocity of 6m/s, what is the mass of the second car? Q2: (20marks) 1. The parking brake on a 1200kg automobile has broken, and the vehicle has reached a momentum of 7800kg.m/s. What is the velocity of the vehicle? (10 marks) 2. Suppose that the acceleration of an object is zero. Does this mean that there are no forces acting on it? (5 marks) 3. When a basketball player dribbles a ball, it falls to the floor and bounces up. Is a force required to make it bounce? Why? If a force is needed, what is the agent? (5 marks)