[填空题]
A 920-kg sports car collides into the rear 9 jsmw 3ncwepo)p-*o 27*a akienoh sqsg;nar6ua* b, a);r* 8xyd of a 2300-kg SUV stopped at a red light. The bumpers lock, the brakes are locked, and the two cars skid forwo , g*uaash n*r;6;x)ay8sbrqard 2.8 m before stopping. The police officer, knowing that the coefficient of kinetic friction between tires and road is 0.80, calculates the speed of the sports car at impact. What was that speed?(Let A represent the sports car, and B represent the SUV) $\approx$ m/s
