a 10 kg sled slides down a snowy hill. At position A it is moving at 1.00 m/s when it reaches position B it is moving at 3 m/s. Finally it passes position C moving at 1.00 m/s again. Position C is 3.00 m lower than position A and 1.00 m lower than position B. The coefficient of kinetic friction varies from place to place in the snow. What is the work done by friction on the sled as it moves from A to C?