I am doing a project and one of the questions is to find the average force lost to friction. We measured a ball going down a "roller coaster" (it had 2 humps on it). WE have all the speeds and distances and accelerations, Now i calculated the energy lost to friction by taking the initial gravitational energy and subtracting the gravitational energy and kintetic energy after the first drop. So now I have the W in W=F x d but I cant figure out how to get the distance. Is there a way to calculate it or do I have to go measure it? It doesnt have a constant acceleration so I cant think of how I could calculate it.