2) C10B.8 A 1000-kg car traveling at 20 m/s runs into a brick wall, which exerts a constant force on the car as the car's front end crumples. In the process, the car's center of mass moves forward about 0.50 m. Consider the car the system and ignore friction (the car rolls freely). a) Explain why none of the external forces acting on the car do any work on the car. b) What is the magnitude of the force that the wall exerts on the car, and how do you know? c) By how much does the car's internal energy increase? Justify your result