A car weighing 900 kg is waiting at a stop sign. A car weighing 1200 kg hits the oter car. The cars move .76 m after the collision. The coefficient of friction between the sliding tires and the pavement is .92. I need to find the speed of the car right before the collision. I dont know what to use. Conservation of momentum doesnt work because I need at least one of the velocities.I can get the work done by friction fairly easily. But i can't get anywhere from there.