AF Physics 1 Homework - Work and Energy A 2. An m = 2 kg block slides on a flat, smooth track with an initial speed of v; = 2 m/s. The block slides down a rough incline that has a length L = 5 m and a vertical height h = 0.3 m onto another flat, smooth track. The block's final speed is v = 3 m/s. (a) How much work is done by the force of friction as the block slides down the rough incline? Don't just show calculations; explain what you are doing