I am doing a science fair project in which I am trying to find the relationship between skid distance and cone length. In class we used paper cones which were lined up at the bottom of a ramp (as seen in the attached image) and a marble was released. The marble then, after rolling, entered the paper cone and skid distance of the cone was recorded. So, for science fair, I made different length cones between 10 and 30 cm and through my data I saw a direct relationship between the length of the cone and the skid distance. My only question is why does this occur? I need some ideas as to where to start my research, if anyone knows and could help. THANKS!