Answer Happy

7. A Smart Car is sitting at a red light when it is struck from behind by a large delivery van. After the collision, the two vehicles stick together and skid 2.72 meters into the intersection before stopping. The car has a mass of 982 kg, and the truck has a mass of 7250 kg. The effective coefficient of friction between the tires and the pavement can be considered to be 0.757. a) (3 pts) Draw a diagram showing the cars at three points: just before the collision, just after the collision, and when the cars come to a stop. Place appropriate labels for mass, velocity, and kinetic energy at all three points. b) (4 pts) How fast were the two vehicles stuck together traveling immediately after the collision? c) (4 pts) The car owner's insurance company wants to know how fast the truck was traveling when it hit the car. Find that velocity, in m/s and miles per hour. d) (5 pts) Use the concepts of momentum, impulse, and force to explain why "crumple zones” in cars can help in surviving a collision.