Skid Marks: When there is a vehicle accident, the police are called in to investigate. One part of the investigation is to often estimate the speed the car was traveling at the time of the accident. Using the length of skid marks on the road, police can use a formula to determine within reasonable error the minimum speed of the car at the time. bold italic S space equals square root of 30 d f end root space space space bold left parenthesis bold italic n bold italic o bold italic t bold italic e bold space bold italic t bold italic h bold italic a bold italic t bold space bold italic t bold italic h bold italic e bold space bold italic f bold italic o bold italic r bold italic m bold italic u bold italic l bold italic a bold space bold italic i bold italic g bold italic n bold italic o bold italic r bold italic e bold italic s bold space bold italic b bold italic r bold italic a bold italic k bold italic e bold space bold italic e bold italic f bold italic f bold italic i bold italic c