A collision occurred when a 1500-kg car collided with a 15 OOOkg truck. The truck was initially at rest. After the collision, the vehicles locked together and moved with a combined velocity of 1.0 m/s, east. D 2. Use the law of conservation of momentum to solve for the velocity of the car, in metres per second, before the collision occurred. (3 marks) D 3. Convert your answer from D2 into kilometers per hour. The posted speed limit in this area was 25 km/h because it was designated for loading passengers and freight. Was the car speeding? (1 mark) D 4. In answering this question you have made the assumption that momentum is conserved. However, the system was not isolated! The car and truck have rubber tires and the friction between the tires and the ground is significant. HOWEVER, momentum is indeed conserved. How can we simply ignore friction in our calculations, without introducing substantial error? (4 marks)