SJ_Alg

= **Cars** =

**Crime-scene investigators use the formula s=√30fd for the length of skid marks, d (in feet), and the coefficient of friction, f (for condition of the road and the type of road), to determine the speed, s (miles per hour)to determine how fast a car was going just before it was involved in a car accident. The length of the skid marks and the coefficient of friction can determine the speed of the car at the moment before the impact. **  **If the coefficient of friction for an icy road is .15 and a car ran into the median during an ice storm and left skid marks 300 feet long, the car was going approximately 40 miles per hour.**


 * If the coefficient of friction for an icy road is .15 and the car ran into the a median during an ice storm and left skid marks 300 feet long, the car was traveling around 40 miles per hour. **
 * The rate of speed the car was traveling depends on the weather. In icy weather the distances are different. **

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 * If the coefficient of friction for a dry road is .8 and a car left skid marks 132 feet long, the car was going approximately 56 miles per hour. **




 * In a court room situation, a person can argue they were only going 45 miles per hour, crime-scene investigators can use a formula to determine if they are telling the truth or not. If the road was dry the skid marks should be about 84 feet long. **


 * by Tessa Kraemer and Laura Linsmeier **