Speed at the bottom of a hill - Please help!! 1. The problem statement, all variables and given/known data Bike (mass 40kg) traveling down a hill. Speed at the top of the hill is 5.0 m/s. The hill is 10m high and 100m long. Force of friction is 20N, what is the speed at the bottom? 2. Relevant equations The only formula I've tried is v(final) = Sq. rt. of 2gy(initial). I don't know what y is, where friction plays into this and obviously I'm not getting the answer. Please help! 3. The attempt at a solution I have converted the units to kg, and m, and drawn a picture. I know that the answer is 11 m/s but there isn't a formula or very similar problem in my book. (The only similar problem doesn't account for friction so I don't really know where to begin.