Officer Matthews received a more detailed report from the police accident investigator: A 1978 Ford was 30 feet into the cross walk, coming to a stop. A 1988 Chevrolet van was found directly behind the car. Both vehicles showed skid marks from the south side of the crosswalk to the position where they came to a stop. Our analysis showed that the Ford left an 80-foot skid mark prior to being struck by the van, while the van left a 20-foot skid mark prior to impact.
A drag sled was used to determine that the average deceleration on the road was 19 ft/s2. The speed limit on Rebel Drive is 15 mph. The van weighs approximately twice the weight of the car, and since the car was stopped just prior to impact, speed of the van prior to impact was approximately 1.5 times the speed of the two vehicles just after impact.
1. Using what you know about reaction time and stopping distance, how far from the cross walk was Sandy when she first saw the students?