fictional force problem....given a slope(grade)??? A 1000kg car is moving down a road with a slope(grade) of 15% at a constant speed of 15m/s. What is the direction and magnitude of the frictional force? So... V= 15m/s a= 0 (constant) The slope really throws me off..I don't know where to start! And the percent.... What am I supposed to do with that??