Hi everyone. I have another problem that is just stumping me. I posted this earlier and still can't understand it. Here it is... A 1-kg ball starting at h = 6.1 meters slides down a smooth surface where it encounters a rough surface and is brought to rest at B, a distance 18.3 meters away. To the nearest joule what is the work done by friction? Imagine the ball starting on top of a waterslide, sliding down with no friction, and then coming down onto the straight path that slows you down. I can find the Potential Energy of the ball, but don't know where to go from there! Pls help!