[填空题]
A 920-kg sports car collides into the rear end of a 2300-kg SUV stopped a-sg)4bqv9 y,c1 ki imzi7/fe t+1xbt5 l6d jwvt 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 coefficient of kinetic friction between tires and road is 0.80, calculates the speed of the sports car at impact. What wej+5il w17t/t6fxv bdas that speed?(Let A represent the sports car, and B represent the SUV) $\approx$ m/s
