(it) a 1.0 x 10^3 kg toyota collides into the rear end of a 2.2 x 10^3-kg cadillac stopped at a red light. the bumpers lock, the brakes are locked, and the two cars skid forward 2.8 m before stopping. the police officer, knowing that the coefticient of kinetic fric- tion between tires and road 1s 0.40, calculates the speed of the toyota at impact. what was that speed?