Need help!!!! A 1.0x10^3 kg Toyota collides into the rear end of a 2.2x10^3 kg Cadillac stopped at a red light. The bumpers lock, the brakes are locked, and the two cars skid forward 2.8m before stopping. The police officer, knowing that the coefficient of Kinectic friction between the tires and road is 0.40, calculates the speed of the Toyota at impact. What was that speed?