Atraffic accident detective measures the skid marks left by a car, 825kg. he determines that the distance between the point that the driver slammed on the brakes and the point where the car came to a stop was 34.0 m. from a reference manual he determines that the coefficient of kinetic friction between the tires and the road under the prevailing conditions was 0.300. how fast was the car going when the driver applied the brakes? (this car was not equipped with anti-lock brakes.

Car batteries are often rated in amp-hours. this rating indicates the quantity of charge that can pass through the battery before the battery's chemical energy must be restored by the car's generator or some other source. the amp-hour unit is convenient for simple calculations. for example, a 60-amp-hour battery can supply a current of 1.0 a for 60 h (or 60 a for 1.0 h) before going dead. find the energy stored in the following. (a) a 58 a-h, 10 v car battery(b) a 1.3 a-h, 1.7 v flashlight battery