1. The problem statement, all variables and given/known data "A little girl is sliding down a snowy hill on her sledge and out on a horizontall flat area. The girl has a physic intrested mom which wants to know what the maxium speed the sledge can reach. She measures that the hill is 3,0m high and 6,0m long. The sledge slides for 12.5m before stoping. She belives that the friction power on the hill is 85% of hte friction power of the flat area. What is the highest maxium speed the sledge can reach? The answer is supposed to be 6.5m/s This is my terible drawing i made 2. Relevant equations W=-Rs Ek =1/2 mv^2 Ep= mgh Ek+Ep=Ek0+Ep0+W 3. The attempt at a solution At the end i reach V=sqrt(mgh/(1.85*0.888)), which equals to the wrong answer.. I dont even know. i have tried to solve this for like 2 hours now and its driving me crazy. Any help would be apprecieated a lot. Sorry for the bad english, i translated the problem from Norwegian to English.