1. At an accident scene on a level road, investigators measure a car's skid marks to be 88 m long. It is a rainy day. The coefficient of friction between the tires of the car and the road is estimated to be 0.42. Determine the speed of the car just before the driver slammed on the brakes. (Hint: Ff does work to stop the car.)
2. In the 1950s, an experimental train that had a mass of 25000 kg was powered across a level track by a jet engine that produced a thrust of 500000 N for a distance of 500 m. What would be the speed of the train after this distance?